Goldfish and koi

Reliance is placed on physical and chemical methods of water purification. Zeolite will absorb ammonia excreted by the fish, while activated charcoal will adsorb many harmful chemicals from the water.

Fig 14-2. Clinical aquarium setup.

Antibiotics can be administered either by:

1. Injection. Optimum site is either immediately in front or behind the dorsal fin in the midline.

2. In feed (but note that many sick fish are inappetant)

3. Bath (may damage biological filtration)

4. Gavage.

Analgesia

Butorphanol at 0.05 to 0.5 mg/kg IM

Anesthesia

There are a number of anesthetic preparations and protocols described, but the author has found MS222 and benzocaine to be the most useful.

Suitable anesthetic agents

1. MS222

a. This is a benzocaine derivative with a sulfonate radical, giving it water solubility (and increased acidity). It is absorbed and primarily excreted across the gill epithelium. Hypoxia can be a problem.

b. MS222 can be added directly to water in incremental doses, but fish may show mild signs of distress due to a rapid fall in pH. As a rough guide, sedation is achieved at 20 to 50 mg/L and anesthesia at 50 to 100 mg/L.

c. To avoid this, dissolve in saturated solution of NaHCO3 to form a buffered stock solution of 10 g/L (10,000 ppm).

d. Recovery from short procedures is rapid (koi (see also Musculoskeletal Disorders)

• Lymphocystis (iridovirus)—large, cauliflower-like masses on fins and skin; does not usually infect cyprinids, but may be seen in other pond or coldwater fish, such as sunfish (Lepomis spp.)

• Epitheliocystis—looks like lymphocystis, but can infect cyprinids, including carp

• Myxosporidae—obvious nodules; often fish displays dark or accentuating coloring, weight loss, whirling, and fin rot

• Henneguya koi—small, smooth rounded cystlike nodules in the skin; can also affect the gills and internal organs

• Ichthyophonus hoferi—wasting, darkening of skin color, and obvious boil-like swellings in the skin; in extreme cases it may have a sandpaper effect, due to the large number of granulomas present. Also exophthalmia, abnormal behavior, and abnormal swimming patterns (if the central nervous system is invaded). See also Neurologic and Swimming Disorders, Ophthalmic Disorders, and Systemic Disorders.

• Gas-filled bubbles in the skin, especially on the fins; also occasionally behind the eye (gas bubble disease—usually secondary to oxygen supersaturation)

• Hypersensitivity reactions at attachment sites of parasites such as Argulus and Lernea

Changes in pigmentation or color

• Reddened fin and skin. Bacterial infection (see “Erosions and Ulceration” above), golden shiner virus (Notemigonus crysoleucas only), spring viremia of carp (SVC; see Systemic Disorders), grass carp rheovirus (Ctenopharygodon idella only)

• Graying skin secondary to excessive mucus production (ectoparasites, especially Chilodonella, Trichodina—Fig. 14-5)

• White tufts on surface, may look like cotton wool (Epistylis, Saprolegnia, Cytophaga-like bacteria). In pond fish, fungal infections that have been present for some time may be green or brown due to secondary colonization by algae. Note: Mucous strands hanging from the skin can strongly resemble Saprolegnia.

• Staff s disease—Saprolegnia fungal growths present only in the nostrils; seen in common carp in Poland during the winter months in 1- to 2-year-old carp

• Obvious discrete white spots (Ichthyophthirius). In koi, there is often a “salt and pepper” dusting appearance rather than distinct white spots.

• Dark or accentuating coloring (Myxosporidae)

• Dusty effect over body surface (Oodinium, velvet disease)

• Gray spots on gills and fins (Glocchidia, larval freshwater mussels)

Fig 14-5. Excess mucus on a koi with a Chilodonella infestation.

• Whitish mucous tufts on hood (or wen) of fancy goldfish (see also Ophthalmic Disorders)

• Color fading—in goldfish and koi it is likely to be a nutritional lack of appropriate carotenoids. Some goldfish on good diets do spontaneously turn white—this is likely to be genetic.

• Occasionally areas of dark pigment develop on the red areas of koi, particularly seen in kohakus. Known to koi keepers as shimmies, these are merely changes in pigmentation and do not warrant removal except for aesthetic purposes.

Ectoparasites

• Protozoa

• Chilodonella (see also Respiratory Tract Disorders)

• Trichodina, Trichodonella, and Triparciella (see also Respiratory Tract Disorders)

• Ichthyodo necator (Costia necatrix—see also Respiratory Tract Disorders)

• Epistylis (Heteropolaria)

• Ichthyophthirius multifiliis (white spot—see also Respiratory Tract Disorders)

• Oodinium (velvet disease)

• Myxosporidea

- Henneguya koi

- Thelohanellus nikolskii

- Thelohanellus hovorkai (myxosporean—Yokohama et al 1999)

• Helminths

• Gyrodactylus (skin flukes)

• Dactylogyrus (gill flukes—see also Respiratory Tract Disorders)

• Leeches (e.g., Piscicola geometra)

• Molluscs

• Glocchidia (larval freshwater mussels—see also Respiratory Tract Disorders)

• Crustaceans

• Argulus spp.

• Eearnea spp. (anchor worm)—obvious Y-shaped parasites

• Neoplasia

• Carp pox (CHV-1, see above)

• Squamous cell carcinoma (possibly triggered by CHV-1—Fig. 14-6)

• Erythrophoroma (especially koi)

• Fibromas (especially goldfish—Fig. 14-7)

• Papillomas. Note: The lesions induced by CHV-1 histologically resemble papillomas.

Disorders of the fins

• Disorders of the fins largely follow those of the skin and are usually symptomatic of a more widespread dermal problem.

Fig 14-6. Squamous cell carcinoma in a carp.

Fig 14-7. Fibroma on a lionhead goldfish.

• Occasionally fins suffer traumatic injury and will split between the rays or even fracture the rays. Often these heal uneventfully. Occasionally suturing may be undertaken to improve the aesthetic result.

• Damaged or diseased distal sections of the fins can be resected, and usually the fin will regenerate over time.

Other findings on clinical examination

• Clamped fins, depression, sudden death (Chilodonella, golden shiner virus)

• Skin ulceration, respiratory breathing problems

• Fish usually appear depressed, fins clamped shut, may “wobble” as they swim or even “shimmy," skin appears dull and grayish; ulceration may be seen, respiratory signs (Ichthyobodo)

• Breathing difficulties, irritation; fins clamped (Ichthyophthirius, Oodinium)

• Dark or accentuating coloring, weight loss, whirling and fin rot (Myxosporidea)

• Open skin sores, wasting and protruding eyes, possible spinal curvature (Mycobacteriosis)

• Exophthalmia, hemorrhages in grass carp (grass carp rheovirus)

• Gas bubbles behind eye (gas bubble disease)

• Darkened body color, ascites, skin hemorrhages, anal prolapse (SVC)

Investigations

1. Skin scrape and microscopy (Fig. 14-8)

a. Protozoa

i. Trichodina, Trichodonella, and Triparciella: Circular, rotating parasites around

40 μm

ii. Ichthyophthirius: Large ciliate, horseshoe-shaped nucleus

iii. Chilodonella: Large protozoan (30 to 70 μm) that has an almost oval, flattened appearance. Obvious cilia; moves with gliding, slow circular movement

iv. Oodinium: Can be quite large, up to 1.0-mm diameter, oval-shaped with a very dark appearance because of chloroplasts. Not usually mobile

Fig 14-8. Common fish ectoparasites (freshwater—not drawn to scale).

b. Flukes

i. Gyrodactylus: Live-bearing; can usually see large H-shaped hooks of both adult and unborn young

ii. Dactylogyrus: Egg layer. Usually four black spots at caudal end. Can be quite large flukes

2. Radiography

3. Routine hematology and biochemistry

4. Culture and sensitivity

5. Endoscopy

6. Biopsy

a. Intranuclear inclusions present with CHV-1 infections

b. Polymerase chain reaction (PCR) for SVC

7. Ultrasonography

8. Postmortem examination

9. Viral isolation for SVC

10. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Management

1. See under Nursing Care.

2. Skin lesions and ulcers

a. Maintain good water quality.

b. Clean once with topical iodine.

c. If large/deep, then cover with barrier substance such as Orabase (Squibb) to reduce further secondary contamination and form a partial osmotic barrier.

3. Antibiotic cover:

a. Enrofloxacin at 5 mg/kg IM every other day or as a bath at 2.5 mg/L for 5 hours s.i.d.

b. Marbofloxacin at 5 mg/kg IM every 3 days

4. Alter management to reduce risk of recurrence.

TreatmentZspecific therapy

• Gas bubble disease

• Oxygen supersaturation usually secondary to pressurized oxygenation (e.g., waterfalls, malfunctioning Venturi pumps), excess photosynthesis (high plant levels, suspended algae)

• Correct source of problem.

• Rarely fatal—fish usually recover uneventfully.

• Bacterial septicemia and ulceration

• See “Management” above.

• Debridement of ulcers followed by packing with protective layer, such as Orabase (Squibb)—see Nursing Care

• Some may benefit from long-term salt bath (see Nursing Care) to reduce osmotic gradient.

• Sunburn

• Treat as for bacterial ulceration above.

• Oodinium

• Try a proprietary velvet treatment.

• Metronidazole bath at 50 mg/L bath for up to 24 hours daily for 10 days

• Quinine hydrochloride added to water at 10 to 20 mg/L tank water indefinitely. Some fish are sensitive to this.

• The encysted stage is relatively resistant to chemical attack.

• Can colonize the intestines of fish, where again it can be protected from medications

• Antibiotic cover should be considered as secondary infections are common at the areas where the skin is damaged.

• Eliminate the parasite from a show aquarium by removing all fish, reducing or cutting out the light levels, and raising the temperature to 30 to 32° C for 3 weeks.

• Ichthyophthirius multifiliis—white spot

• Proprietary white spot remedy

• Raising water temperature 1 or 2° C speeds up life cycle, promoting the exposure of the chemical-sensitive motile theront stage.

• Epistylis (Heteropolaria)

• Commercial ectoparasitic preparations

• Chilodonella

• Proprietary ectoparasitic medications

• Glacial acetic acid dips at 8 mL/gallon for 30 to 45 seconds; may kill weak fish

• Chilodonella prefers temperatures of 18 to 22° C, but for Chilodonella cyprini, temperatures of 5 to 10° C seem to be close to its optimum.

• Trichodina, Trichodonella, and Triparciella

• Proprietary ectoparasitic medication

• Ichthyobodo

• Standard proprietary antiprotozoan treatments

• Remove all of the fish from the infected aquarium or pond for 24 to 48 hours as the parasite can only survive without a host for a few hours.

• Ichthyobodo is able to survive temperatures down to 2° C and can cause mortality in overwintering carp.

• Henneguya koi and Thelohanellus spp.

• No effective treatment

• Common carp are more susceptible to Thelohanellus nikolsii than koi or goldfish (Molnar 2002).

• T. hovorkai requires an intermediate oligochaete host.

• Feeding a diet of 0.1% fumagillin prevented mortality in Thelohanellus-infected koi (Yokohama et al 1999).

• Flukes (skin, gill)

• Proprietary ectoparasitic preparations

• Praziquantel at 10 mg/kg body weight PO; as a 1- to 2-hour bath at 15 to 20 mg/L. With larger fish, in-feed medication at a rate of 400 mg/100 g food daily for 7 days

• Dactylogyrids are egg layers; the egg stage is resistant to treatment and so infestations require multiple treatments up to 4 weeks apart depending on water temperature.

• Glocchidia (larval freshwater mussels): Usually self-limiting. Larvae only transiently parasitic

• Whitish tufts on hood. This is normal and may be linked to normal hood growth. No treatment needed

• Grass carp rheovirus

• No treatment. Symptomatic treatment only

• Golden shiner virus

• No treatment. Symptomatic treatment only

• SVC

• No treatment. Symptomatic treatment only

• Leeches

• Remove individual parasites.

• Treat with organophosphates (where legal to do so).

• Learnea (anchor worm)

• Remove individual parasites.

• Treat with lufenuron (Program, Novartis) at 0.088 mg/L as a once-only treatment.

• Treat with organophosphates (where legal to do so).

• Argulus (fish louse)

• Remove individual parasites.

• Treat with lufenuron (Program, Novartis) at 0.088 mg/L as a once-only treatment.

• Treat with organophosphates (where legal to do so).

• A potassium permanganate bath at 10 ppm (mg/L) for 5 to 60 minutes can be used to rid both individual fish and plants of this parasite.

• Dermocystidium koi

• Surgical removal

• Consider itraconazole at 1.0 to 5.0 mg/kg PO every 1 to 7 days, either in feed or gavage.

• Saprolegnia (fungal disease)

• Proprietary medications containing malachite green

• Remove visible hyphae and swab the affected area with a 10% povidone-iodine solution once daily.

• Maintain the fish in a salt solution as this will not only help to control the fungal infection but will also help with the osmotic imbalance resulting from the infection. Even salt solutions as low as 10 parts per thousand (mg/100 mL) will inhibit Saprolegnia infections. Ideally aim for 1 to 3 g/L as a permanent solution until the problem has resolved.

• Carp pox (CHV-1)

• No treatment. Will usually clear up in warmer water, but recrudescence common

• Lymphocystis

• No direct cure. Usually self-limiting

• Ozone or ultraviolet sterilization may reduce spread.

• Attempted surgical removal is usually followed by recurrence.

• Epitheliocystis

• Chlamydophila-like organism

• Some antibiotics (e.g., chloramphenicol) recorded as effective

• SVC—see Systemic Disorders

• Neoplasia

• Chemotherapy in fish is in its infancy.

• Surgical removal followed by treatment of surgical wound as described under “Management” above

• Surgical debulking followed by injection of cisplatin directly into the tissue mass on a weekly basis

Respiratory tract disorders

Viral

• Koi herpesvirus (KHV; cyprinid herpesvirus 3, CHV-3)

• Gill necrosis virus

Bacterial

• Bacterial (environmental) gill disease

Fungal

• Branchiomycosis

Protozoal

• White spot (Ichthyophthirius)

• Chilodonella (see also Skin Disorders)

• Ichthyobodo (Costia) necatrix

• Oodinium (velvet disease) (see also Skin Disorders)

• Trichodina, Trichodonella, and Triparciella (see also Skin Disorders)

• Henneguya koi (see also Skin Disorders)

• Myxosoma dujardini

Parasitic

• Dactylogyrus spp. (gill flukes)

• Glocchidia (larval freshwater mussels)

• Ergasilus (gill maggot—large crustacean parasite)

Neoplasia

• Gill neoplasia

Other noninfectious problems

• Hypoxia (high stocking levels, high temperatures, low atmospheric pressure)

• Poor water quality; can cause gill damage that predisposes to bacterial gill disease

• Ammonia toxicity (see also Neurologic and Swimming Disorders)

• Nitrite toxicity

• Malachite green toxicity

• Stress

Findings on clinical examination

• Moderate to extreme respiratory effort

• Rapid gill ventilation

• Apparent gasping at water surface

• Hemorrhage from the gills in koi following handling (stress)

• Gray spots on gills and fins (Glocchidia, larval freshwater mussels)

• Mottled colored gills, necrotic gills, or patches on gills; weak, lethargic

(branchiomycosis; severe bacterial gill disease; in carp, koi—KHV, gill necrosis virus; Fig. 14-9)

• Mass deaths in koi only; goldfish, rudd, orfe, etc., unaffected (KHV)

• Extensive gill damage and hemorrhage (Sanguinicola inermis)

• Damaged gills, obvious large parasites (Ergasilus)

• Excess mucus production, clamped fins, depression, sudden death (Chilodonella, Ichthyobodo)

• Clamped fins; scratching and flashing; inactivity (gill flukes)

• Thickened gills, mucus trailing from gills (bacterial gill disease)

• Dusty effect over body surface (Oodinium—velvet disease)

• Cystic nodules on the gills (Myxosoma dujardini, Henneguya koi)

Fig 14-9. Gill lesions of koi herpesvirus.

• Permissive temperature range for KHV (18 to 25° C)

• Brown discoloration of gills (nitrite toxicity—methemoglobin formation)

Investigations

1. Water quality tests, especially ammonia, nitrite, nitrate, pH, temperature

2. Check dissolved oxygen levels.

3. Gill scrape (“wet” prep under light microscope)

4. Radiography

5. Routine hematology and biochemistry

6. Culture and sensitivity

7. PCR for KHV

8. Endoscopy

9. Biopsy

a. Gill and other organs: Typical intranuclear inclusions for KHV. Note: Also seen with carp pox (CHV-1)

10. Ultrasonography

11. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Management

1. See Nursing Care.

2. Improve water quality.

3. Vigorous aeration

TreatmentZspecific therapy

• Ammonia toxicity

• Partial water changes to dilute the ammonia levels

• Adding zeolite will absorb large quantities of ammonia.

• Longer-term control may include addition of commercially available Nitrosomonas bacterial cultures or equivalent.

• Nitrite toxicity

• Adding salt to the water to a concentration of 0.3%, the equivalent of 3.0 kg/1000 L, can be beneficial (chloride ions compete with the absorption of nitrite ions).

• Partial water changes

• Addition of extra-bacterial (Nitrobacter) cultures in the form of commercially available freeze-dried or suspended cultures may be of some benefit.

• Dietary vitamin C may have a protective function, although its effect is less than that of salt.

• Malachite green toxicity

• Improved management only

• Malachite green binds irreversibly to respiratory enzymes, so increased aeration may not be beneficial.

• Hypoxia

• Increase water turnover by use of pumps and airstones to maximize gaseous exchange at the surface.

• Reduce stocking density.

• Pump liquid oxygen into water.

• Gill necrosis virus: No treatment

• KHV

• No treatment

• Reducing temperatures to below the permissive range may halt mortalities.

• Koi can be “vaccinated” by exposing them to the virus at 23° C for 3 to 5 days and then transferring these fish to water held at the nonpermissive temperature of 30° C. Such koi usually have high levels of KHV-specific antibodies.

• KHV is notifiable in the UK and reportable in USA, Canada and Australia.

• Bacterial gill disease

• Correct any underlying environmental problem.

• Chloramine-T at 10 mg/L in pond/aquarium—use less in soft water, down to 2 mg/L

• Appropriate antibiosis

• Branchiomycosis

• No known effective antifungals

• Consider itraconazole at 1.0 to 5.0 mg/kg PO every 1 to 7 days, either in feed or gavage.

• Chilodonella

• Proprietary ectoparasitic medications

• Glacial acetic acid dips at 8 mL per gallon for 30 to 45 seconds; may kill weak fish

• Chilodonella prefers temperatures of 18 to 22° C, but for Chilodonella cyprini, temperatures of 5 to 10° C seem to be close to optimum.

• Ichthyobodo necator (Costia necatrix)

• Usual ectoparasitic treatments

• Remove all of the fish from the infected aquarium for 24 to 48 hours, as the parasite can only survive outside the host for a few hours.

• Ichthyobodo is able to survive temperatures down to 2° C and can cause mortalities in overwintering carp.

• Oodinium (velvet disease)

• Proprietary velvet treatment

• Metronidazole bath at 50 mg/L bath for up to 24 hours daily for 10 days

• Quinine hydrochloride added to water at 10 to 20 mg/L pond/aquarium indefinitely; some fish are sensitive to this

• The encysted stage is relatively resistant to chemical attack.

• Can colonize the intestines of fish, where again it can be protected from medications

• Antibiotic cover should be considered as secondary infections are common at the areas where the skin is damaged.

• Eliminate the parasite from a show aquarium by removing all fish, reducing or cutting out the light levels. and raising the temperature to 30 to 32° C for 3 weeks.

• Ichthyophthirius multifiliis—white spot

• Proprietary white spot remedy

• Raising water temperature 1 or 2° C speeds up life cycle, promoting the exposure of the chemical-sensitive motile theront stage.

• Trichodina, Trichodonella, and Triparciella

• Proprietary ectoparasitic medication

• Myxosoma dujardini and Henneguya koi

• No effective treatment

• Glocchidia (larval freshwater mussels)—usually self-limiting. Larvae only transiently parasitic

• Flukes (skin, gill)

• Proprietary ectoparasitic preparations

• Praziquantel at 10 mg/kg PO or at 10 mg/L for a 3-hour bath

• Dactylogyrus spp. are egg layers; the egg stage is resistant to treatment, so praziquantel should be repeated every 2 to 4 weeks depending on temperature, for at least 3 doses.

• Sanguinicola

• Praziquantel at 10 mg/kg PO in food

• Control of snail intermediate hosts where possible

• Ergasilus

• Individual removal of parasites

• Organophosphates (where legal to do so)

• Ivermectin at 0.1 to 0.2 mg/kg IM. May be toxic to goldfish; may be persistent in environment

• Treat with lufenuron (Program, Novartis) at 0.088 mg/L as a once-only treatment.

Gastrointestinal tract disorders

Protozoal

• Eimeria spp., esp. E. carpelli and E. subepithelialis (young carp and koi)

Parasitic

• Nematodes

• Camallanus spp.

• Raphidascaris acus (Dezfuli et al 2000)

• Helminths

• Bothriocephalus spp.

• Khawia spp.

Nutritional

• Constipation/diarrhea (especially fancy goldfish—see also Nutritional Disorders)

Neoplasia

• Buccopharyngeal neoplasia

• Gill neoplasia

• Intestinal adenocarcinoma

Other noninfectious disorders

• Foreign body (e.g., piece of gravel), especially goldfish

Findings on clinical examination

• Emaciation, sunken eyes

• Diarrhea

• Anorexia

• Long trails of feces; may contain gas bubbles. Loss of balance (constipation/diarrhea)

• Weight loss; big head in carp. Swollen abdomen. May cause mass mortalities in young koi (tapeworms)

• Obvious red worms protruding from anus, especially with live-bearers. Ulceration around anus may be apparent. Weight loss (Camallanus)

• Dysphagia (buccopharyngeal neoplasia, pharyngeal foreign body)

• Swimming with mouth permanently open (pharyngeal foreign body)

Investigations

1. Light microscopy

2. Fecal sample

a. Flotation

3. Radiography

4. Routine hematology and biochemistry

5. Culture and sensitivity

6. Endoscopy

7. Biopsy/necropsy

a. Larvae of Raphidascaris acus (European minnow Phoxinus phoxinus)

8. Ultrasonography

9. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Treatment/specific therapy

• Eimeria spp.

• May respond to anticoccidial drugs such as amprolium as a continuous bath at 10 mg/L for 7 to 10 days or to sulfonamide antibiotics

• Constipation/diarrhea

• Feed higher fiber foods, such as shelled peas, live or frozen invertebrates (e.g., Daphnia or bloodworm, Chironomus larvae).

• Nematodes

• Levamisole bath at 2 mg/L for up to 24 hours

• Fenbendazole at 20 mg/kg body weight given 7 days apart

• Mebendazole at 20 mg/kg for 3 treatments given at weekly intervals

• Camallanus has both a direct and indirect life cycle (small crustaceans such as Cγclops act as intermediate hosts).

• Tapeworms

• Praziquantel at 10 mg/kg mixed in food once only

• Control of intermediates

- Bothriocephalus: Intermediate stages in copepods

- Khawia: Intermediate stages in tubulicid worms

• Neoplasia

• Usually inoperable by the time it is identified

• Accessible tumors may be managed by injecting cisplatin directly into the tissue mass on a weekly basis as a debulking exercise.

Nutritional disorders

• Hypovitaminosis E (sekoke disease—carp/koi)

• Wasting when fed on vitamin E-deficient diet—classically a diet of silkworm larvae only

• Supplement with vitamin E or feed a commercially complete diet.

• Hypovitaminosis C

• Poor immune function; spinal deformities, possibly secondary to effects of collagen and cartilage integrity

• Hepatic lipidosis

• Too high a protein and carbohydrate diet; often fed to achieve maximum growth rates in koi

• Switch to lower energy foods and supplement with vitamin E.

• Constipation/diarrhea

• Difficult in practice to distinguish between the two

• Typically a problem with fancy goldfish characterized by long trails of feces

• Gas bubbles may be present in the feces; in the gut these may cause a loss of balance, mimicking swimbladder disease.

• Feed higher fiber foods, such as shelled peas, live or frozen invertebrates (e.g., Daphnia or bloodworm—Chironomus larvae).

Hepatic disorders

Protozoal

• Chloromyxum cyprini and C. koi

Nutritional

• Hepatic lipidosis (see Nutritional Disorders)

Neoplasia

• Hepatocellular tumors

Findings on clinical examination

• Vague signs of ill health

• Unexpected mortalities in “healthy” fish

• Large females particularly susceptible (hepatic lipidosis)

• Incidental finding of protozoa in gallbladder (Chloromyxum spp.)

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

7. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

TreatmentZspecific therapy

• Hepatic neoplasia

• Usually no viable treatment; often sizable by the time of diagnosis

• Chloromyxum spp.

• Usually incidental finding. No effective treatment

Pancreatic disorders

Parasitic

• Nematodes

Neoplasia

Findings on clinical examination

• Vague signs of ill health

• May be incidental finding

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

7. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Treatment/specific therapy

• Nematodes (see Gastrointestinal Tract Disorders)

Cardiovascular and hematologic disorders

Bacterial

• Endocarditis

Protozoal

• Hemoparasites (see Systemic Disorders)

• Trypanoplasma borreli (see also Urinary Disorders)

• Trypanosoma carassii

• Trypanosoma danilewskyi

Parasitic

• Sanguinicola inermis (see Respiratory Tract Disorders)

Neoplasia

Other noninfectious problems

• Cardiomyopathy

Findings on clinical examination

• Apparent respiratory disease secondary to anemia (see also Respiratory Tract Disorders)

• Ascites, bloated abdomen

• Exophthalmos (see also Ophthalmic Disorders)

Investigations

1. Radiography

2. Routine hematology and biochemistry

a. Cytology: Stained blood smears for hemoparasites

3. Culture and sensitivity

4. Endoscopy

5. Biopsy/necropsy

6. Ultrasonography

7. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Management

• See Nursing Care.

• Keeping fish in a permanent 5-g/L solution of salt (not table or rock salt) will reduce the osmotic load on a sick koi or goldfish.

TreatmentZspecific therapy

• Vegetative endocarditis

• Antibiotics

• Guarded prognosis

• Hemoparasites

• Methylene blue at 60 mg/kg leave as is per day PO for 4 days

• Metronidazole at 50 mg/kg PO per day

• Note: The leech Piscicola geometra acts as a vector for Trypanosoma danilewskyi.

Systemic disorders

Viral

• SVC (rhabdovirus)

• Lymphocystis (iridovirus)—usually forms masses on skin but rarely occurs in coelom (see Skin Disorders)

• CHV-1 (in carp fry self-limiting but may cause significant problems internally

• Ichthyophonus hoferi

• No efficacious treatment available

• CHV-1

• No efficacious treatment available

• CHV-2

• Triggered by stress and more common in temperatures in low 20s° C. In United States more common in spring and fall when temperatures are suitable

• No treatment, but losses can be reduced by transferring out of permissive temperature range (e.g., 26 to 30° C)

• Metabolic acidosis

• Difficult to treat; best avoided by patient, low-stress capture techniques involving two nets (use one net to guide the fish toward the other)

Musculoskeletal disorders

Bacterial

• Mycobacteriosis (fish tuberculosis), primarily Mycobacterium marinum, M. fortuitum, M. cheloni, occasionally other Mycobacterium spp. implicated

Fungal

• Dermocystidium koi

Nutritional

• Hypovitaminosis C (see Nutritional Disorders)

• Tryptophan deficiency

• Sekoke disease (see Nutritional Disorders)

Neoplasia

Other noninfectious problems

• Electrocution (see Neurologic and Swimming Disorders)

• Organophosphate exposure

• Trauma

Findings on clinical examination

• Spinal curvature/scoliosis (mycobacteriosis, electrocution, trauma, hypovitaminosis C, tryptophan deficiency, organophosphates)

• Open skin sores, wasting, and protruding eyes with or without spinal curvature (mycobacteriosis)

• Cysts in skin and muscles (Dermocystidium)

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

7. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Treatment/specific therapy

• Mycobacteriosis

• Antibiotic treatment often not very effective

• Kanamycin bath at 50 mg/L every 48 hours for four treatments was successful in guppies (Conroy and Conroy 1999)

• Consider euthanasia, especially because of zoonotic risk.

• Dermocystidium koi

• See Skin Disorders.

• Spinal curvature/scoliosis

• Treatment difficult. Surgical internal fixation to stabilize condition has been attempted (Govett et al 2004).

• Tryptophan deficiency

• Supplement with tryptophan.

Neurologic and swimming disorders

Viral

• SVC (swimbladder inflammation—see Systemic Disorders)

Bacterial

• CNS infection/granuloma

Fungal

• Ichthyophonus hoferi

• CNS infection/granuloma

Protozoal

• Myxosporidea (see also Skin Disorders)

• Myxosoma encephalina

• Sphaerospora renicola

Neoplasia

• Internal neoplasia compressing swimbladder

Other noninfectious problems

• Electrocution/lightning strike—sudden-onset spinal deformities, sudden death, especially in pond fish (Pasnik et al 2003)

• Whirling and erratic swimming, dark or accentuating coloring, weight loss, and fin rot; there may be obvious nodules (Myxosporidea)

• Poor water quality, especially high ammonia and/or nitrite levels—new tank/pond syndrome

• Sudden-onset poisoning, such as from zinc (galvanized buckets, etc.), pesticides

• Swimbladder dysfunction, a particular problem with fancy goldfish. Often due to anatomical malformation of swimbladder in fancy breeds of goldfish but can be due to infection (bacterial, fungal) or compression from surrounding organs (e.g., gonadal neoplasia)

• Abnormal swimbladder functioning secondary to compression from internal space­occupying lesions (e.g., neoplasia)

• Swimbladder torsion

• Hypothermia (koi)

Findings on clinical examination

Sudden darting movements, loss of balance, rapid respiration (water quality, poisoning) Loss of balance—unable to swim down from surface or up from bottom (swimbladder dysfunction, enteritis, SVC)

Fish, especially koi, may need to permanently swim in order to maintain position in water column; may regularly gulp at surface as attempts to inflate swimbladder via pneumatic duct (swimbladder disease/compression)

Koi lying on side at bottom, sluggish movements, water temperature close to freezing (hypothermia)

Swimbladder signs but in carp fry (Sphaerospora)

• Wasting, darkening of skin color, and obvious boil-like swellings in the skin; also exophthalmia, abnormal behavior, and abnormal swimming patterns (Ichthyophonus)

• Abnormal swimming posture, whirling (Myxosporidea, Myxosoma encephalina)

Investigations

1. Water quality tests

2. Radiography for swimbladder disease (Figs. 14-10 to 14-12)

3. Routine hematology and biochemistry

4. Culture and sensitivity

5. PCR test for SVC (notifiable in UK, reportable in United States, Canada, and Australia)

6. Virus isolation for SVC

7. Endoscopy

8. Biopsy

9. Ultrasonography

10. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Management

• Maintain optimum water conditions.

Treatment/specific therapy

• Poor water quality

• Address which parameter(s) are abnormal. Multiple partial water changes often beneficial in short term. Many need to review stocking, filtration system, or husbandry management.

Fig 14-10. Comparative radiograph of a normal goldfish showing relative size and position of the cranial and caudal sections of the swimbladder (labeled).

Fig 14-11. Same view of a fantail goldfish showing poor inflation of the caudal portion of the swimbladder.

Fig 14-12. Diagrammatic explanation of Figures 14-10 and 14-11.

• Ammonia toxicity

• Partial water changes to dilute the ammonia levels

• Adding zeolite will absorb large quantities of ammonia.

• Longer term control may include addition of commercially available Nitrosomonas bacterial cultures or equivalent.

• Swimbladder disease

• Usually no effective treatment for fancy goldfish. May develop ulceration on areas persistently floating above water level

• Pneumocystocentesis can provide temporary relief, but the problem is likely to recur.

• Try antibiotics if suspect bacterial infection

• If goldfish is floating can implant small sterile counterweight into ventral coelomic cavity, but is difficult to judge correct weight

• Pneumocystoplasty has been attempted (Britt et al 2002) and with refinement could prove useful.

• Enteritis may trigger gas formation in the gut, mimicking swimbladder dysfunction. Offer high-fiber feeds such as live or frozen bloodworm or Daphnia.

• Surgical removal of internal neoplasia

• SVC (see Systemic Disorders)

• Swimbladder torsion

• Surgical correction

• Hypothermia

• Usually seen in larger koi kept in ponds that are too shallow and where the temperature falls close to freezing. Typically these koi were introduced as small specimens but have since grown. For large koi the pond should be at least 120 cm deep.

• Where possible, remove koi to warmer water or more suitable accommodation.

• Will usually self-correct as conditions improve but may predispose to further swimbladder complications

• Sphaeropsora renicola

• Fumigillin at 1 g/kg food for 10 to 14 days for prevention

• Myxosporidea/Myxosoma encephalina

• No effective treatment. Try fumigilin as above.

• Ichthyophonus hoferi

• No efficacious treatment available

• CNS infection/granuloma

• Attempt antibiotic or antimycotic treatment. Poor prognosis

• Electric shock

• Supportive treatment

Ophthalmic disorders

Viral

• Grass carp rheovirus (grass carp Ctenopharyngodon idella—see Skin Disorders)

Bacterial

• Mycobacteriosis (see also Musculoskeletal Disorders and Skin Disorders)

• Retrobulbar granuloma

• Bacterial keratitis (often Cytophaga-like bacteria).

Fungal

• Fusarium spp. (see also Skin Disorders)

• Ichthyophonus hoferi (see also Neurologic and Swimming Disorders, Skin Disorders, and Systemic Disorders)

• Retrobulbar granuloma

Protozoal

• Ichthyophthirius

Parasitic

• Diplostomum (intermediate stage of avian tapeworm)

Nutritional

• Riboflavin deficiency

• Ascorbic acid deficiency

• Hypovitaminosis A

Fig 14-13. Overgrowth of the eye by the hood of an oranda goldfish.

Neoplasia

• Retrobulbar neoplasm

Other noninfectious problems

• Overgrowth of the eye by the hood in certain breeds of fancy goldfish, such as lionheads and orandas (Fig. 14-13)

• Gas bubble disease (see Skin Disorders)

• Cataracts

• Erythrophoroma

• Cardiomyopathy

Findings on clinical examination

• Exophthalmia (grass carp rheovirus, SVC, retrobulbar mass, cardiomyopathy)

• Opacity of the cornea—keratitis

• Opacity of lens in eye

• Corneal ulceration

• Blindness. Fish may be able to compensate to some extent by use of lateral line.

• Exophthalmia accompanied by wasting, darkening of skin color, and obvious boil-like swellings in the skin, abnormal behavior, and abnormal swimming patterns (Ichthyophonus hoferi)

• Gas bubbles around and behind eye (gas bubble disease)

• Glaucoma (usually secondary to intraocular disease)

• Overgrowth of both eyes by exuberant growth of the hood in fancy goldfish

Investigations

1. Ophthalmic examination

2. Radiography

3. Routine hematology and biochemistry

4. Culture and sensitivity

5. PCR test for SVC (notifiable in UK, reportable in United States, Canada, and Australia)

6. Virus isolation for SVC

7. Endoscopy

8. Biopsy

9. Ocular ultrasonography

10. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

TreatmentZspecific therapy

• Ichthyophonus hoferi

• No efficacious treatment available.

• Diplostomum

• No effective treatment

• Consider praziquantel at 10 mg/kg body weight PO; as a 1- to 2-hour bath at 15 to 20 mg/L. With larger fish, in-feed medication at a rate of 400 mg/100 g food daily for 7 days. This should eliminate the cestode, but there is unlikely to be any resolution of ocular damage.

• Attempt to break life cycle by:

- Control of aquatic snails as source of disease

- Preventing predation by birds (primary hosts)

• Glaucoma

• Enucleation

• Cataracts

• Aging change; occasionally can be due to nutritional deficiencies (e.g., riboflavin deficiency or parasitism), but these are rare.

• In globe-eyed goldfish is very common

• Corneal ulceration

• Systemic antibiosis

• Scarification and application of tissue glue can protect the cornea and aid reepithelialization.

• Erythrophoroma

• If partially or completely covering the cornea, then a superficial keratectomy may be necessary. Treat subsequently as for corneal ulceration.

• Overgrowth of hood

• Resect part of hood covering eye under general anesthesia.

Urinary disorders

Bacterial

• Nephritis

Protozoal

• Hoferellus carassii (goldfish)

• Hoferellus cyprini (carp)

• Trypanoplasma borreli—see Cardiovascular and Hematologic Disorders (Meyer et al 2002)

Neoplasia

Other noninfectious problems

• Polycystic renal disease (goldfish)

Findings on clinical examination

• Lethargy

• Ascites

• Swollen abdomen in goldfish, loss of balance, scales not protruding (Hoferellus carassii, polycystic renal disease); differentiate from ascites—see Systemic Disorders

• Carp cease feeding, are “off color,” deaths after 7 to 14 days (H. cyprini)

• Abdominal distension, exophthalmus, swimming disorders (“sleeping sickness”—

T. borreli)

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy/necropsy

a. Progressive nephritis (T. borreli)

b. Dilated renal tubules and collecting ducts; trophozoites or spores visible (H. carassii)

c. Trophozoites or spores visible (H. cyprini)

6. Ultrasonography

7. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

TreatmentZspecific therapy

• Polycystic renal disease

• Genetic disorder—autosomal recessive. No treatment

• Hoferellus spp.

• No reliable treatment

• Try toltrazuril at 30 mg/L as a 60-minute bath every other day for 3 treatments.

• Intermediate stages found in tubulicid worms.

• Trypanoplasma—see Cardiovascular and Hematologic Disorder.

Reproductive disorders

Neoplasia

• Ovarian neoplasia

• Testicular neoplasia

Other noninfectious problems

• Egg retention

Findings on clinical examination

• Pronounced swelling of the coelomic cavity; may be asymmetrical (gonadal neoplasia) or symmetrical (egg retention)

• Other differentials for a symmetrical swollen coelom

• Scales not prominent (in goldfish consider also Hoferellus, polycystic kidney disease— see Urinary Disorders)

• Scales prominent—ascites (see Systemic Disorders)

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

7. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

TreatmentZspecific therapy

• Gonadal neoplasia

• Surgical resection

• Egg retention

Treatment of egg retention

Goldfish

1. Buserelin at a 1: 10 dilution applied to the gills or 10 μg∕kg IM

2. hCG at 700 to 1000 IU/kg IM

3. In both cases, followed by manual stripping 6 to 12 hours later

Koi

1. In general koi will only respond to injections of carp pituitary extract.

2. Maintain temperature around 25° C.

3. Priming dose of 0.3 mg/kg of reconstituted carp pituitary extract

4. Second dose of 3.0 mg/kg 12 to 18 hours later

5. Attempt manual stripping 6 to 12 hours later.

6. Cool temperatures (for skin disorders

Pruritus

• Ectoparasites

• Poor water quality

Erosions and ulceration including fin rot

• Bacterial disease, typically Aeromonas spp., Cytophaga-like bacteria, and Flavobacterium spp.; also mycobacteriosis (see Musculoskeletal Disorders)

• Ulceration, hemorrhage, darkening of color, and exophthalmos in cichlids (streptococcal infections)

• Often secondary to trauma or ectoparasites (especially Tetrahymena, Ichthyobodo)

• Flexibacter columnaris—whitish erosive areas, especially along back of fish, mouth fungus and shimmying (mollies), and tail rot (guppies). Sometimes known as false neon tetra disease when it occurs on small tetras.

• In snakehead, striped snakehead skin ulcerative disease (rhabdovirus)

• Fusarium mycosis—may also cause blindness

• Aphanomyces invadens mycosis (epizootic ulcerative syndrome, EUS). Susceptible species include striped snakehead (Channa striata), giant gourami (Osphronemus goramy), and silver barb (Barbodes gonionotus); see Miles et al 2001

• Channel catfish virus disease is a herpesvirus that affects fry and fingerling catfish. Infected fish swim erratically, are pale with multiple skin hemorrhages, severe exophthalmia, and swollen abdomens.

• Lymphosarcoma (see “Neoplasia”)

Nodules and nonhealing wounds

• Large, cauliflower-like masses on fins and skin (Lymphocystis—an iridovirus; Fig. 15-2)

• Uneven skin surface in angelfish, Pterophyllum spp. (Pleistophora)

• Lip fibroma in angelfish, Pterophyllum spp. (suspected retrovirus; Francis-Floyd et al 1993)

is invaded; Ichthyophonus hoferi—see also Neurologic and Swimming Disorders, Ophthalmic Disorders and Systemic Disorders)

• Pentastomids

• Gas-filled bubbles in the skin, especially on the fins; also occasionally behind the eye (gas bubble disease—usually secondary to oxygen supersaturation)

• Yellowish cystic lesions up to 5 mm diameter (Clinostomum spp., a digenetic trematode; Wildgoose 1998)

Changes in pigmentation and color

• Lethargy and reddened areas of skin; fish stop feeding (bacterial septicemia, Edwardsiella ictaruli in catfish)

• Obvious discrete white spots visible on skin and fins (Ichthyophthirius multifiliis, white spot disease)

• Whitened areas of muscle, often accompanied by loss of color, especially with neon tetras, other small tetras, and killifish. Also may see emaciation and spinal curvature (Pleistophora—neon tetra disease). In white angelfish may cause localized accumulations of melanophores producing “black holes”

• Dark or accentuating coloring, obvious nodules, weight loss, whirling, and fin rot (Myxosporidea)

• Darkened colors, emaciation, abnormal swimming behavior, and mortalities in tilapia (Piscirickettsia-like organisms, PLO); some respiratory signs (gill hyperplasia)

• Enhanced coloration, especially Malawi cichlids (hemoparasites); may see wasting

• White tufts on surface that may resemble cotton wool (Epistylis, Saprolegnia, Flexibacter columnaris). Note: Mucous strands hanging from the skin can strongly resemble Saprolegnia.

• “Mouth fungus” (along with fin rot) is often described as a fungal infection, especially in live-bearers such as mollies and guppies. This is usually due to Cytophaga-like bacteria such as Flexibacter columnaris.

• Graying skin (due to excessive mucus production—ectoparasites, typically Trichodina, Chilonodella, Ichthyobodo, Gyrodactylus, Dactylogyrus)

• Multiple small black spots in the skin and deeper in the muscles (so-called black spot disease; Digenetic trematodes, e.g., Neascus). The blackened cysts appear particularly obvious in light-colored fish such as silver dollars (Metynnus argentius).

• Darkening of body coloration, lethargy, loss of appetite, abdominal distension, and mortalities in varieties of the three spot gourami (Trichogaster trichopterus); also mortalities in the dwarf gourami (Colisia lalia)—an unspecified iridovirus

• Black spots—melanin concentrations—described in Mycobacterium marinum skin granulomas in Oreochromis mossambassicus (Noga et al 1990)

• Darkened color, weight loss, excessive mucus production, rapid respiration, lethargy (discus plague—discus, occasionally angelfish, Pterophyllum spp.; see Systemic Disorders)

• Algal dermatitis in farmed Metriaclima zebra has been described associated with deep invasion and persistent skin infections with Chlorochytrium and Scenedesmus spp. of algae.

• Color fading—likely to be nutritional lack of appropriate carotenoids

• Planaria (flatworms) visible in aquaria—rarely cause problems; usually due to overfeeding. Consider praziquantel (toxic to Corydoras catfish).

Ectoparasites

• Protozoa

• Ichthyophthirius multifiliis (white spot disease)

• Oodinium (velvet disease)—dusty effect over body surface

• Tetrahymena—whitish areas or “spots” often with ulceration; more common on live-bearers, cichlids (particularly dwarf cichlids), and tetras; often associated with bacterial infections and white spot

• Ichthyobodo necator (Costia necatrix)—common on catfish, killifish, anabantids, swordtails (Xiphophorus spp.) and cichlids; see also Respiratory Tract Disorders

• Epistylis (Heteropolaria)

• Chilodonella

• Spironucleus

• Trichodina, Trichodonella, and Triparciella

• Myxosporidea, including Henneguya, Myxidium, and Mitaspora

• Helminths

• Gyrodactylus, Enterogyrus, and Cichlidogyrus spp. (skin flukes)

• Digenetic trematodes (black spot disease)

• Clinostomum spp.

• Leeches

• Batracobdella tricarinata (Negm-Eldin and Davies 1999; see also Cardiovascular and Hematologic Disorders)

• Flatworms on glass and substrate (Planaria)—not parasitic, but may indicate overfeeding

• Molluscs

• Anodonites trapesialis (Silva-Souza and Eiras 2002)

• Crustaceans

• Argulus (fish louse)

• Livoneca (usually on wild-caught South American fish); see also Respiratory Tract Disorders

• Pentastomes

Neoplasia

• Lymphosarcoma—start as nodules in the skin; eventually the overlying skin becomes devitalized and sloughs, leaving an ulcer. Internal lesions may also occur. Lymphosarcoma has been identified in pike (Esox spp.) and Malawi cichlids (Metriaclima spp.)

• Xiphophorus (swordtails and platies) hybrids are very prone to developing melanomas and neuroblastomas. Note: At least three viruses, a papovavirus and two retroviruses, have been implicated as predisposing factors.

• Papillomas

• Odontomas appear as swellings around the mouth on freshwater angelfish (Pterophyllum spp.).

• Lip fibroma in angelfish (Pterophyllum spp.)—suspected retrovirus (Francis-Floyd et al 1993)

Other findings on clinical examination

• Loss of fins and/or eyes

• Irritation, ulceration (ectoparasites)

• Breathing difficulties, irritation, fins clamped (Ichthyophthirius, Oodinium, Trichodina—see also Respiratory Tract Disorders)

• Clamped fins, depression, sudden death (Chilodonella)

• Slimey droppings, weight loss, no appetite, secondary infections (Spironucleus)

Investigations

1. Skin scrape under light microscopy (see Fig. 14-8)

a. Protozoa

i. Chilodonella is a large protozoan (30 to 70 μm) that has an almost oval, flattened appearance. Obvious cilia; moves with gliding, slow circular movement

ii. Ichthyobodo: Even on high power, a small comma-shaped, very mobile parasite seen gyrating through the water

iii. Oodinium: Can be quite large, up to 1-mm diameter, oval-shaped with a very dark appearance because of chloroplasts; not usually mobile

iv. Trichodina, Trichodonella, and Tripartiella: Circular, rotating parasites around 40 μm

v. Ichthyophthirius: Large ciliate, horseshoe-shaped nucleus

vi. Epistylis: Stalked, cup-shaped ciliates in colonies

b. Flukes

i. Gyrodactylus: Live-bearing; can usually see large H-shaped hooks of both adult and unborn young

ii. Dactylogyrids: Egg layer; usually four black spots at caudal end; can be quite large

c. Fungi

i. Saprolegnia: A meshwork of mycelium and fruiting bodies should be easily identifiable.

ii. Ichthyophonus: Squash preparation of nodule. The spores can be readily seen as spherical bodies, varying from 10 to 100 μm in diameter. There is much variation in the appearance of these multinucleated spores.

2. Radiography

3. Routine hematology and biochemistry

4. Culture and sensitivity

5. Endoscopy

6. Biopsy

7. Ultrasonography

8. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Management

• See Nursing Care.

TreatmentZspecific therapy

• Gas bubble disease

• Oxygen supersaturation usually secondary to pressurized oxygenation (waterfalls, malfunctioning Venturi pumps, etc.), excess photosynthesis (high plant levels, suspended algae)

• Correct source of problem.

• Rarely fatal—fish usually recover uneventfully.

• Algal dermatitis

• No treatment; usually of no consequence to the fish

• Lymphocystis

• No direct cure. Usually self-limiting

• Ozone or ultraviolet sterilization may reduce spread.

• Attempted surgical removal is usually followed by recurrence.

• Striped snakehead skin ulcerative disease (viral infection)

• No treatment

• Channel catfish virus disease

• No treatment

• Covering antibiotics as it may be secondary infections that cause mortalities

• Bacterial infections

• Antibiotics

• Debridement of ulcers followed by packing with protective layer, such as Orabase (Squibb)

• Change management system (e.g., separation of aggressive individuals, removal of damaging aquarium furniture, improved water quality).

• Flexibacter columnaris

• Antibiotics

• Copper-based medications can work.

• Surfactants such as benzalkonium chloride are useful as a bath. Note: Toxicity of benzalkonium chloride is increased in soft water, so doses should be reduced if used in soft water (or if hardness not known) and the fish monitored closely for signs of distress.

• Recommended dose rate for benzalkonium chloride (Table 15-4)

• Improved management

• PLO

• Antibiotics

• Mycobacteriosis

• Difficult to treat; potential zoonosis

• Kanamycin bath at 50 mg/L every 48 hours for 4 treatments was successful in guppies (Conroy and Conroy 1999).

• Ichthyophonus hoferi

• No efficacious treatment available.

• Ichthyophthirius multifiliis white spot

• Proprietary white spot remedy

• Raising water temperature 1 or 2° C speeds up life cycle, promoting the exposure of the chemical-sensitive motile theront stage.

• Oodinium

• Proprietary velvet treatment

• Metronidazole bath at 50 mg/L for up to 24 hours daily for 10 days

• Quinine hydrochloride at 10 to 20 mg/L indefinitely. Some fish are sensitive.

• The encysted stage is relatively resistant to chemical attack.

• Can colonize the intestines of fish, where again it can be protected from medications

• Antibiotic cover should be considered, as secondary infections are common at the areas where the skin is damaged.

• Eliminate the parasite from a show aquarium by removing all fish, reducing or cutting out the light levels, and raising the temperature to 30 to 32° C for 3 weeks.

• Tetrahymena

• Predisposes to secondary infections

• Often found associated with Ichthyophthirius

• Poor environmental conditions (high ammonia, high organic load, low water temperatures) predispose (Pimenta Leibowitz et al 2005).

• Try proprietary ectoparasitic medication. Can spread internally through the body musculature, so treatment may not work.

• Chloramine-T at an average dose rate of 10 mg/L—use less in soft water, down to 2 mg/L.

• Recommended chloramine-T concentrations for different pH and water hardness combinations (Table 15-5)

• Epistylis (Heteropolaria)

• Commercial ectoparasitic preparations

• Chilodonella

• Proprietary ectoparasitic medications

• Glacial acetic acid dips at 8 mL/gallon for 30 to 45 seconds; may kill weak fish

• Trichodina

• Proprietary ectoparasitic medication

• Flukes (skin, gill)

• Proprietary ectoparasitic preparations

• Praziquantel at 10 mg/kg body weight by mouth; as a 1- to 2-hour bath at 15 to

20 mg/L. With larger fish, in-feed medication at a rate of 400 mg/100 g food daily for 7 days. Toxic to Corydoras catfish

• Dactylogyrids are egg layers; the egg stage is resistant to treatment and so infestations require multiple treatments up to 4 weeks apart depending on water temperature.

• Digenetic trematodes

• Complex life cycle involving a primary host such as a piscivorous bird, reptile or fish, and secondary snail hosts, so they rarely become a problem in aquaria.

• Treat with praziquantel as described above for skin flukes.

• Alternatively treat in a bath for 1 hour with a combination of salt, acriflavine, and formalin or in the aquarium with acriflavine and salt only for 36 hours. Care with Corydoras catfish

• Hemoparasites (e.g., Trypanosoma spp.)

• Methylene blue at 60 mg/kg per day PO for 4 days, or metronidazole at 50 mg/kg PO per day

• Myxosporidea. No treatment available. Try IUmagillin at 1 g/kg food for 10 to 14 days for prevention.

• Neon tetra disease (Pleistophora)

• No good treatment. Options would include:

- Feeding a diet of 0.1% IUmagillin

- Toltrazuril at 30 mg/L as a 60-minute bath every other day for 3 treatments

• Transmitted via consumption of infected cadavers or food crustaceans (cyclops)

• Spironucleus

• Treat with metronidazole.

• Dimetridazole appears to be linked with sterility in fish.

• Fusarium mycosis

• No effective treatment

• Aphanomyces invadens (EUS)

• No effective treatment

• Temperature-dependent pathology; EUS not seen at 32° C but does occur at lower temperatures (20° C)

• Saprolegnia (fungal disease)

• Proprietary medications containing malachite green

• Remove visible hyphae and swab the affected area with a 10% povidone-iodine solution once daily.

• Maintain the fish in a salt solution, as this will not only help to control the fungal infection but will also help with the osmotic imbalance resulting from the infection. Salt solutions as low as 10 parts per thousand (ppt) (mg/100 mL) will inhibit Saprolegnia infections. Ideally aim for 1 to 3 g/L as a permanent solution until the problem has resolved. Care with Corydoras catfish

• Usually secondary invader, so may need to treat underlying ulceration and secondary bacterial infections

• Anodontites trapesialis

• Larval stages described as parasitizing the epidermis of the cichlid Tilapia rendalli and the suckermouth catfish Hypostomus regani (Silva-Souza & Eiras 2002)

• Little inflammatory response, but multiple microscopic skin lesions may predispose to secondary skin infections.

• Usually self-limiting. Larvae only transiently parasitic

• Fish louse (Argulus) or Livoneca

• Individual removal of parasites

• Treat with lufenuron (Program, Novartis) at 0.088 mg/L as a once-only treatment.

• Treat with organophosphates where legal.

• Placing fish in a potassium permanganate bath at 10 ppm (mg/L) for 5 to 60 minutes can be used to rid both individual fish and plants of this parasite. Care with sensitive species

• Pentastomids

• No treatment

• Prevent by removal of other hosts from life cycle, especially reptile predators (e.g., turtles, snakes).

• Discus plague

• Unknown cause. No effective treatment. May be linked to, or initiated by, stress

• Lip fibromas, odontomes, neoplasia

• Debulking/surgical removal

• Surgical debulking followed by injection of cisplatin directly into the tissue mass on a weekly basis

Respiratory tract disorders

Note that many freshwater fish can utilize atmospheric air. Lungfish (Protopterus spp.), anabantids—including the popular gouramis (Trichogaster spp.), fighting fish (Betta spp.), and paradise fish (Macropodus spp.)—and some South American catfish, such as Hypostomus punc- tatus and Corydoras, are common examples. Gulping for air in these species may not neces­sarily indicate a respiratory problem.

Bacterial

• Bacterial gill disease

• PLO in tilapia—see also Skin Disorders

Fungal

• Fungal gill diseases

Protozoal

• Oodinium (velvet disease—see Skin Disorders)

• Trichodina (see Skin Disorders)

• Ichthyophthirius (white spot), especially catfish (see Skin Disorders)

• Ichthyobodo necator (Costia necatrix—see also Skin Disorders)

• Cryptobia iubilans (indirect—respiratory signs secondary to anemia—see Systemic Disorders)

• Myxosporidea, including Henneguya (especially Corydoras catfish), Myxidium, and Myxobolus

Parasitic

• Helminths—Dactylogyrus (gill flukes)

• Crustaceans—Livoneca

Neoplasia

• Gill tumors are common in Poecilia hybrids (molly-guppy).

Other noninfectious problems

• Hypoxia

• Ammonia toxicity (see also Neurologic and Swimming Disorders)

• Nitrite toxicity

• Malachite green toxicity

• Overturned operculae in dragonfish (Sclerophages spp.) and arowanas

(Osteoglossum spp.)

• Complete or partial absence of operculae (unilateral or bilateral)

Findings on clinical examination

• Moderate to extreme respiratory effort

• Rapid gill ventilation

Fig 15-3. A group of discus with high respiratory rates aggregate at the surface in one corner. Contrast this with the behavior of fish in the other aquaria.

• Apparent gasping at water surface or at areas of high turbulence, such as water inlets (Fig. 15-3)

• Anemia (chronic disease, Cryptobia)

• Breathing difficulties, dusty effect over body surface (Oodinium)

• White spots on skin/fins (Ichthyophthirius); white spots not always obvious

• Visible gill flukes

• Respiratory distress, clamped fins, flashing; one-sided breathing in discus (Dactylogyrus)

• Fish usually appear depressed, fins clamped shut, may “wobble” as they swim or even “shimmy"; skin appears dull and grayish; ulceration may be seen; respiratory signs (Ichthyobodo)

• Brown color to gills (nitrite toxicity)

• Respiratory signs, darkened colors, emaciation, abnormal swimming behavior, and mortalities in tilapia (PLO)

• Large woodlouse-resembling parasite (Livoneca)—up to 2.5 cm long; the adult parasites burrow into the gills and mouth cavity, but they may also attach and burrow into the flank. Livoneca are protoandrous hermaphrodites. The larger female is often found in the mouth, while the smaller male is attached to the gills.

• The soft edging to the operculum gradually curls outward and can become permanently deformed (overturned operculae).

Investigations

1. Gill scrape under light microscopy

a. Thickening of the secondary lamellae (gill hyperplasia)

b. Large ciliate, horseshoe-shaped nucleus (Ichthyophthirius)

c. Chilodonella: A large protozoan (30 to 70 μm) that has an almost oval, flattened appearance; obvious cilia; moves with gliding, slow circular movement

d. Oodinium: Can be quite large, up to 1-mm diameter, oval-shaped with a very dark appearance because of chloroplasts; not usually mobile

e. Circular, rotating parasites around 40 μm (Trichodina, Trichodonella, and Triparciella)

2. Radiography

3. Routine hematology and biochemistry

4. Culture and sensitivity

5. Endoscopy

6. Biopsy

7. Ultrasonography

8. Water quality parameters

a. Check temperature, ammonia, nitrite, nitrate, and pH values.

b. Recommended levels of oxygen are above 6 mg/L at 25° C for tropical freshwater fish.

Management

• Improve circulation and/or aeration.

TreatmentZspecific therapy

• Ammonia toxicity

• Partial water changes to dilute the ammonia levels

• Adding zeolite will absorb large quantities of ammonia.

• Longer-term control may include addition of commercially available Nitrosomonas bacterial cultures or equivalent.

• Nitrite toxicity

• Partial water changes

• Salt (chloride ions compete with nitrite binding sites at the gills). Ideally aim for 1 to

3 g/L as a permanent solution until the problem has resolved. Care with Corydoras catfish

• Commercially available Nitrobacter cultures (long term)

• Malachite green toxicity

• Improved management only

• Malachite green binds irreversibly to respiratory enzymes, so increased aeration may not be beneficial.

• Bacterial gill disease

• Correct any underlying environmental problem.

• Consider surfactants such as:

- Chloramine-T (see "Tetrahymena" in Skin Disorders)

- Benzalkonium chloride (see "Flexibacter" in Skin Disorders)

• Fungal gill disease

• As for bacterial gill disease

• Salt at 1 to 3 g/L as a permanent solution until the problem has resolved if Saprolegnia involved. Caution: Corydoras catfish may be sensitive to salt.

• PLO

• Antibiotics

• Oodinium (velvet disease—see Skin Disorders)

• Chilodonella

• Proprietary ectoparasitic medications

• Glacial acetic acid dips at 8 mL/gallon for 30 to 45 seconds; may kill weak fish

• Chilodonella prefers temperatures of 18 to 22° C.

• Ichthyobodo

• Standard proprietary antiprotozoan treatments

• With species of fish able to cope with high temperatures (like discus and fighting fish, Betta spp.), raise the temperature to over 30° C.

• Remove all of the fish from the infected aquarium for 24 to 48 hours as the parasite can only survive away from the host for a few hours.

• Dactylogyrus spp.

• Proprietary ectoparasitic preparations

• Praziquantel at 10 mg/kg PO once only or at 10 mg/L for a 3-hour bath. Toxic to Corydoras catfish

• Dactylogyrus spp. are egg layers; the egg stage is resistant to treatment, so praziquantel should be repeated every 2 to 4 weeks depending un temperature, for at least 3 doses. Toxic to Corydoras catfish

• Livoneca

• See Skin Disorders.

• Overturned gill covers

• Linked to poor water quality, especially high ammonia and nitrite levels

• If caught in the early stages, transferring the arowana to highly oxygenated, good-quality water may reverse the condition.

• For advanced cases, surgical removal of the affected part is undertaken.

• This operation is regularly described for the highly prized Asian dragonfish (see Fig. 15-1), but it may be more for aesthetic reasons than of benefit to the fish.

• Partial or complete absence of operculum

• Congenital problem. No treatment

Gastrointestinal tract disorders

Bacterial

• Enteritis

Protozoal

• Protopalina (very large ciliate), especially discus, kissing gouramis

• Spironucleus—especially in discus, angelfish, oscars, and other cichlids (see Skin Disorders)

• Hexamita—especially in cichlids and anabantids

• Cryptosporidium—especially angelfish (Pterophyllum spp.)

• Coccidia

• Piscicryptosporidium cichlidaris—uncertain pathogenicity; encysts deep in the lining of the stomach, so has the potential to cause much damage

• Crytobia iubilans

Parasitic

• Nematodes

• Camallanus spp.

• Spirocamallanus rebecae (Vidal-Martinez and Kennedy 2000)

• Raillietnema kritscheri (Vidal-Martinez and Kennedy 2000)

• Capillaria spp. (esp. discus)

• Atractis vidali (in wild Vieja intermedia and Cichlasoma pearsei) (Gonzalez-Solis and Moravec 2002)

• Contracaecum spp. (in Oreochromis leucostictus)

• Cestodes

• Tapeworms

- Crassicutis cichlasomae (Vidal-Martinez and Kennedy 2000)

- Amirthalingamia spp. (Aloo 2002)

- Cyclustera spp. (Aloo 2002)

- Enterogyrus cichlidarum (tilapine cichlids)

• Thorny-headed worms

• Acanthocephalus spp. (especially wild-caught Malawi cichlids)

• Neoechinorhynchus golvani (Vidal-Martinez and Kennedy 2000)

• Polyacanthorhynchus kenyensis (Aloo 2002)

Nutritional

• Lack of dietary fiber, especially Lake Malawi cichlids: In highly adapted vegetarian cichlids, such as many of the Rift Lake species, a diet low in dietary fiber appears to predispose to Cryptobia iubilans.

• Lack of bogwood: Some loricarid catfish (South American sucking catfish)—particularly some of the panaques—have specialist dietary requirements including bogwood on which to feed. Failure to provide this causes a progressive fading and loss of condition.

• Hypovitaminosis C: Classic sign is spinal curvature, typically in live-bearers. Supplement with vitamin C and increase greens/algae in diet. See Musculoskeletal Disorders.

• Vitamin E deficiency: Muscle wastage, especially large, fast-growing predatory fish fed on dead fish. Supplement with vitamin E, and alter diet appropriately.

• Hepatic lipidosis: Seen often in rapidly growing large fish, such as red-tailed catfish (Phractocephalus), which are fed excessively to maximize growth rate. Reduce feeding and supplement with vitamin E.

Neoplasia

• Buccopharyngeal neoplasia

• Gill neoplasia

Other noninfectious problems

• Incisor teeth overgrowth in pufferfish

• Foreign body

Findings on clinical examination

• Weight loss

• Stunting/poor growth (intestinal parasites)

• Listlessness and weight loss, especially in wild-caught Malawi cichlids (Acanthocephalus)

• Emaciation (coccidiosis)

• Stringy, white feces (Protopalina, Spironucleus, Capillaria, Cryptobia)

• Diarrhea, darkened coloration in discus (Capillaria)

• Anorexia, regurgitation of food, diarrhea, death in angelfish (Pterophyllum spp.—Cryptosporidium)

• Weight loss, poor growth (tapeworms, Enterogyrus cichlidarum)

• Slimy droppings, head and lateral line lesions, weight loss, no appetite, secondary infections (Spironucleus)

• Anorexia, lethargy, and weight loss; some fish may develop ascites (Hexamita)

• In Siamese fighting fish (Betta splendens), Hexamita can cause dropsy-like signs due to multiorgan damage. The liver and kidneys are especially affected.

• In kissing gouramis (Helostoma temmincki), it has been linked to swimming abnormalities, emaciation, white stringy feces, and secondary bacterial infections of the skin.

• Severely affected angelfish will show a distended abdomen and may lie flat at the water surface.

• Less severely affected adult cichlids may have reduced fertility, egg hatchability, and increased loss of fry.

• Obvious red worms protruding from anus, especially with live-bearers; ulceration around anus may be apparent; weight loss (Camallanus)

• Weight loss in spite of good appetite in pufferfish (incisor teeth overgrowth)

• Dysphagia (buccopharyngeal or gill neoplasia, overgrown incisors)

Investigations

1. Anesthetize and examine teeth/oral cavity (especially pufferfish).

2. Light microscopy of feces

a. Large, capsule-shaped ciliated protozoan (Protopalina)

b. Typical capillarid eggs (Capillaria)

3. Radiography

4. Routine hematology and biochemistry

5. Culture and sensitivity

6. Endoscopy

7. Biopsy/necropsy with histopathology

a. Granulomatous gastritis; other organs affected (Cryptobia, mycobacteriosis). Use modified Ziehl-Neelsen (MZN) stain to differentiate (positive for mycobacteriosis).

8. Ultrasonography

9. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Management

• Routine removal of dead fish to prevent scavenging (and hence cross-infection) by other aquarium inhabitants

Treatment/specific therapy

• Protopalina (protozoal parasite)

• Proprietary ectoparasitic medication

• Hexamita

• Metronidazole at 50 mg/L as a bath for up to 24 hours daily for 10 days or as a bath at 5 mg/L every other day for a total of 3 treatments

• Coccidia

• May respond to amprolium as a continuous bath at 10 mg/L for 7 to 10 days

• Potentiated sulfonamide antibiotics:

- 30 mg/kg IM s.i.d. for 7 to 10 days

- 30 mg/kg body weight in feed every 24 hours for 10 to 14 days

• Toltrazuril at 30 mg/L as a 60-minute bath every other day for 3 treatments

• Cryptosporidium

• Treatment is difficult. Consider sulfonamide antibiotics, but success is unlikely.

• Cryptobia iubilans—see Systemic Disorders

• Tapeworms (including Enterogyrus cichlidarum)

• Worming with praziquantel at 10 mg/kg body weight PO; as a 1- to 2-hour bath at 15 to 20 mg/L. With larger fish, in-feed medication at a rate of 400 mg/100 g food daily for 7 days. Toxic to Corydoras catfish

• Avoid feeding live foods to complete life cycle.

• Enterogyrus cichlidarum may escape from the stomach and anterior intestine to invade other organs, such as liver, coelomic cavity, swimbladder, and braincase—see Systemic Disorders (Noga and Flowers 1995).

• Camallanus, Capillaria, and Acanthocephalus

• Levamisole at 2 mg/L for up to 24 hours

• Fenbendazole at 20 mg/kg body weight given 7 days apart

• Mebendazole at 20 mg/kg PO for 3 treatments given at weekly intervals

• Camallanus has both a direct and indirect life cycle (small crustaceans, such as cyclops act as intermediate hosts).

• Incisor teeth overgrowth

• Burr back under anesthetic.

• Offer foods that increase normal wear (e.g., cockles still in shell).

• Foreign body

• Retrieval from stomach, possibly with aid of endoscopy

• Coeliotomy and surgical retrieval

Hepatic disorders

Bacterial

• Hepatitis

• Mycobacteriosis (see Systemic Disorders)

Nutritional

• Hepatic lipidosis (see Nutritional Disorders)

Neoplasia

Other noninfectious problems

• Hypoxia/anoxia (e.g., gill disease—areas of liver necrosis)

• Heavy metal toxicity

Findings on clinical examination

• Nonspecific signs of ill health

• Anorexia

• Loss of balance (displacement of swimbladder)

• Swollen coelom

• Ascites (see Systemic Disorders)

Investigations

1. Radiography

a. Abnormal position of swimbladder secondary to hepatomegaly

2. Routine hematology and biochemistry

a. Raised liver enzymes

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

7. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Management

• Try milk thistle mixed in feed or via gavage.

TreatmentZspecific therapy

• Neoplasia

• No treatment

• Heavy metal poisoning

• Remove suspected source.

• Remove to unaffected water.

• Oxygenate or aerate water well.

Cardiovascular and hematologic disorders

Bacterial

• Endocarditis

Protozoal

• Cryptobia iubilans (see Systemic Disorders)

• Trypanosoma mukasai (Negm-Eldin and Davies 1999)

• Babesiosoma mariae (Negm-Eldin and Davies 1999)

• Cyrilia nili (Negm-Eldin and Davies 1999)

Neoplasia

Other noninfectious problems

• Cardiomyopathy

Findings on clinical examination

• High respiratory rate, anemia (hemoparasites)

• Death occurring within 24 hours of respiratory disease (Cryptobia)

• Ascites (see Systemic Disorders)

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Cytology (hemoparasites)

4. Culture and sensitivity

5. Endoscopy

6. Biopsy

7. Ultrasonography

8. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

TreatmentZspecific therapy

• Bacterial endocarditis

• Antibiosis

• Cryptobia—see Systemic Disorders

• Hemoparasites (Trypanosoma, Babesiosoma, and Cyrilia)

• Methylene blue at 60 mg/kg per day PO for 4 days

• Metronidazole at 50 mg/kg per day PO

• Cardiomyopathy

• No treatments described, possibly due to difficulty in diagnosis. May be worth adapting reptile protocols

Systemic disorders

Viral

• Lymphocystis (iridovirus—see Skin Disorders). Lymphocystis-induced masses can occur internally, acting as space-occupying lesions.

• Rio Grande perch rhabdovirus: Texas cichlid (Herichthys cyanoguttatus), convict cichlid (Archocentrus nigrofasciatum), and Tilapia zilli

• Ramirez dwarf cichlid virus: Ramirez dwarf cichlid (Microgeophagus ramirezi)

• Channel catfish virus disease (herpesvirus)

• PLO: Blue-eyed panaque (Panaque suttonorum)

Bacterial

• Multiorgan systemic infections

• Mycobacteriosis

• Lactococcus garvieae

• Clostridium difficile—possible link with Malawi bloat

Fungal

• Ichthyophonus hoferi—see also Neurologic and Swimming Disorders, Ophthalmic Disorders, Reproductive Disorders, and Skin Disorders.

Protozoal

• Hexamita—see Gastrointestinal Tract Disorders

• Cryptobia—see Musculoskeletal Disorders

• Cryptosporidiosis: Angelfish, Pterophyllum spp.—see Gastrointestinal Tract Disorders

Parasitic

• Enterogyrus cichlidarum—visceral invasion from gut; see Gastrointestinal Tract Disorders

Infectious conditions of unknown etiology

• Discus plague

Nutritional

• See Nutritional Disorders.

Neoplasia

Other noninfectious problems

• Nitrite toxicity

Findings on clinical examination

• Fish may separate themselves from the main group.

• Weight loss, obvious loss of muscle mass of epaxial muscles

• Ascites: Known to aquarists as dropsy, this is often considered a disease in its own right. Typical signs include a swollen abdomen, raised scales, and protruding eyes. Commonly due to multiorgan failure from systemic bacterial infection

• In Siamese fighting fish (Betta splendens), Hexamita can cause dropsy-like signs due to multiorgan damage, in particular the liver and kidneys.

• Hemorrhages and mortalities: Systemic bacterial infections, Lactococcus garvieae

• Spinal curvature, open skin sores, protruding eyes—especially anabantids (mycobacteriosis)

• Erratic swimming, pallor, multiple skin hemorrhages, severe exophthalmia, and swollen abdomens in fry and fingerling channel catfish (Ictarulus punctatus—channel catfish virus disease)

• Progressive loss of appetite and wasting (Cryptobia)—can affect all cichlid species, but it is a particular cause of mortalities in the Rift Lake cichlids. Some of these fish will develop ascites known as Malawi bloat. Note: C. difficile has also been implicated in Malawi bloat.

• Weight loss, darkened color, excessive mucus production, rapid respiration, lethargy (discus plague)—seen in discus (Symphysodon spp.), occasionally angelfish (Pterophyllum spp.); see Skin Disorders

• Lethargy and mortalities in Texas cichlid, convict cichlid, and Tilapia zilli (Rio Grande perch rhabdovirus)

• Lethargy, loss of appetite, incoordination, emaciation, and death in Ramirez dwarf cichlids (Ramirez dwarf cichlid virus)

• Head standing (tiger barbs); respiratory signs (nitrite toxicity)

• Wasting, darkening of skin color, and obvious boil-like swellings in the skin; also exophthalmia, abnormal behavior, and abnormal swimming patterns (if the CNS is invaded); sex reversal in guppies (female to male): Ichthyophonus

• Mortalities in blue-eyed panaque (Panaque suttonorum): PLO

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Postmortem

a. Multiple granulomas in internal organs (mycobacteriosis, Cryptobia); differentiate with MZN (positive for mycobacteria)

7. Ultrasonography

8. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Management

• See Nursing Care.

TreatmentZspecific therapy

• Rio Grande perch rhabdovirus: No treatment

• Ramirez dwarf cichlid virus: No treatment

• Channel catfish virus: No effective treatment

• Antibiotics, as secondary infection is often cause of mortalities

• Ascites (dropsy)

• Without definite diagnosis, prognosis is poor. Attempt use of antibiotic.

• Bacterial infections (including Lactococcus garvieae)

• Antibiotics

• Mycobacteriosis

• Difficult. Potential zoonosis, so euthanasia. See Musculoskeletal Disorders.

• PLO

• Can be treated with a variety of antibiotics

• Cryptobia

• Metronidazole helps but does not appear to eradicate the organism. See "Hexamita" in Gastrointestinal Tract Disorders for suggested dose rates. Yanong et al (2004) found metronidazole ineffective in discus (Symphysodon aequifasciatus), but dimetridazole (80 mg/L for 24 hours repeated daily for 3 days) or 2-amino-5-nitrothiazole

(10 mg/L for 24 hours repeated daily for 3 days) reduced infection.

• In some collections, virtually all the cichlids can be infected and the disease will show itself as a low-grade loss of fish over a period of time.

• Ichthyophonus hoferi

• No efficacious treatment available

• Discus plague

• Unquantified disease; may actually be outbreaks of other undiagnosed diseases such as Hexamita or Capillaria. However, there is some suggestion that an as-yet unidentified infectious agent may be responsible.

• Concentrate on maintaining optimum water quality and minimize stress (e.g., provide hiding places).

• Quarantine all new stock.

Musculoskeletal disorders

Viral

• Chromide iridovirus (chromide cichlids Etroplus maculates, E. canariensis, and E. suratensis)

Bacterial

• Mycobacteriosis—typically M. marinum, M. cheloni, and M. fortuitum

Fungal

Protozoal

• Pleistophora (neon tetra disease)

• Cryptobia iubilans—see Systemic Disorders

Nutritional

• Hypovitaminosis C (especially live-bearers—see Nutritional Disorders)

• Starvation; inappetence, through failure to provide correct environment or diet.

Neoplasia

Other noninfectious problems

• Electroshock (Pasnik et al 2003).

Findings on clinical examination

• Weight loss, muscle wastage (see also Systemic Disorders and Gastrointestinal Tract Disorders)

• In freshwater stingrays (Potamotrygon spp.), weight loss over the pelvic bones can be prominent

• Spinal curvature (hypovitaminosis C, mycobacteriosis, Pleistophora)

• White patches, loss of color, and emaciation (Pleistophora—see Skin Disorders)

• Open skin sores, wasting, and protruding eyes (mycobacteriosis)

• Poor growth (hypovitaminosis C)

• Weight loss and weakness in chromide cichlids Etroplus spp. (chromide iridovirus)

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Postmortem—Multiple granulomas in internal organs (mycobacteriosis, Cryptobia, Flavobacteria); differentiate with MZN (positive for mycobacteria)

7. Ultrasonography

8. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Treatment/specific therapy

• Chromide iridovirus: No treatment

• Pleistophora—see Skin Disorders

• Mycobacteriosis

• Potential zoonosis, so consider euthanasia.

• Treatment problematic; kanamycin bath at 50 mg/L every 48 hours for 4 treatments was successful in guppies (Conroy and Conroy 1999).

• Hypovitaminosis C—see Nutritional Disorders

Neurologic and swimming disorders

Viral

• Ramirez dwarf cichlid virus in Ramirez dwarf cichlid (Microgeophagus ramirezi)

• Deep angelfish disease (herpesvirus): Altum (deep) angelfish (Pterophyllum altum) only. Other Pterophyllum species unaffected

Bacterial

• Flavobacterium spp. (especially live-bearers)

• Streptococcal infections, especially S. iniae

• Bacterial meningitis

• CNS infection/granuloma

Fungal

• Ichthyophonus hoferi—see also Systemic Disorders, Ophthalmic Disorders, Reproductive Disorders, and Skin Disorders

• CNS infection/granuloma

Protozoal

• Myxosporidea—see Skin Disorders

• Hexamita—see Gastrointestinal Tract Disorders

Neoplasia

Other noninfectious problems

• Ammonia toxicity—see also Respiratory Tract Disorders

• Abnormal swimbladder functioning secondary to compression from internal space­occupying lesions (e.g., neoplasia)

• Swimbladder disease

• Swimbladder torsion

• Nicotine toxicity

Findings on clinical examination

• Whirling swimming pattern, dark or accentuating coloring, sudden death (meningitis, Myxosporidea—especially if obvious nodules visible); there may be weight loss and fin rot.

• Swimming abnormalities, emaciation, white stringy feces, and secondary bacterial infections of the skin in kissing gouramis (Helostoma temmincki); Hexamita—see Gastrointestinal Tract Disorders

• Incoordination, muscle spasms, lethargy, loss of appetite, emaciation, and death in Ramirez dwarf cichlids

• Aimless swimming (shimmying), loss of balance, death (Flavobacterium)

• Loss of balance, spinning, pale gills, ulcers, death in altum angelfish (deep angelfish disease)

• Abnormal behavior and abnormal swimming patterns accompanied by wasting, darkening of skin color, and obvious boil-like swellings in the skin; in extreme cases it may have a sandpaper effect, due to the large number of granulomas present; exophthalmia; sex reversal in guppies (female to male): Ichthyophonus

• All or most fish affected: Consider environmental disease (e.g., water quality).

• Upward curling of the disc in freshwater stingrays (Potamotrygon spp.) is often a sign of ill health and is usually either poor water quality or bacterial infection.

• Stiffened pectoral fins, muscular spasms (nicotine toxicity)

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy or postmortem

a. Multiple granulomas (Flavobacterium, mycobacteriosis—see Systemic Disorders)

6. Ultrasonography

7. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

8. Assessment of environment (nicotine toxicity).

TreatmentZspecific therapy

• Ammonia toxicity

• Partial water changes to dilute the ammonia levels

• Adding zeolite will absorb large quantities of ammonia.

• Longer term control may include addition of commercially available Nitrosomonas bacterial cultures or equivalent.

• Deep angelfish disease

• No treatment—supportive only

• Flavobacterium and bacterial meningitis

• Antibiotics

• Ichthyophonus hoferi

• No efficacious treatment available

• Swimbladder disease

• Usually no effective treatment. May develop ulceration on areas persistently floating above water level

• Pneumocystocentesis can provide temporary relief, but the problem is likely to recur.

• Try antibiotics if suspect bacterial infection.

• If the fish is floating, may implant small sterile counterweight into ventral coelomic cavity, but is difficult to judge correct weight

• Pneumocystoplasty (Britt et al 2002) and pneumocystectomy (Lewbart et al 1995) have been attempted and with refinement could prove useful.

• Swimbladder torsion

• Surgical correction

• CNS infection/granuloma

• Attempt antibiotic or antimycotic treatment. Poor prognosis

• Nicotine toxicity

• 10 ppm can kill guppies within 5 minutes.

• Lower doses can cause low-grade mortalities, infertility, and other reproductive problems.

• No direct treatment. Situate air pumps away from smoky atmospheres.

Ophthalmic disorders

Viral

• Channel catfish virus (herpesvirus)—see also Skin Disorders and Systemic Disorders

Bacterial

• Systemic bacterial infection/multiorgan failure

• Retrobulbar granuloma

• Streptococcal infections, especially S. iniae

• Edwardsiella ictaruli (catfish)—see also Skin Disorders

Fungal

• Fusarium mycosis

• Ichthyophonus hoferi—see also Systemic Disorders, Neurologic and Swimming Disorders, Reproductive Disorders, and Skin Disorders

• Retrobulbar granuloma

Protozoal

• Ichthyophthirius

• Tetrahymena

Nutritional

• Riboflavin deficiency

• Ascorbic acid deficiency

• Hypovitaminosis A

Neoplasia

• Retrobulbar neoplasia

Other noninfectious problems

• Traumatic damage or loss of eye; often due to interspecific or conspecific aggression, especially cichlids

• Gas bubble disease—see Skin Disorders

• Cardiomyopathy

• “Drop eye” in dragonfish (Sclerophages spp.) and arowanas (Osteoglossum spp.); (Fig. 15-4).

Findings on clinical examination

• Blindness (Fusarium)

• Exophthalmos, often accompanied by ascites

Fig 15-4. “Drop-eye” in a large silver arowana (Osteoglossum blrchlrrosum).

• Exophthalmos, lethargy, pale skin, sex reversal in guppies (female to male): Ichthyophonus

• Exophthalmos, panophthalmitis, darkening of color, hemorrhage, ulceration in cichlids (streptococcal infections)

• Exophthalmos in channel catfish fry and fingerlings, accompanied by skin hemorrhages, severe abnormal swimming, and swollen abdomen (channel catfish virus)

• Glaucoma—usually secondary to intraocular disease

• One or both eyes is turned permanently downward in arowanas (drop eye).

Investigations

1. Ophthalmic examination

2. Radiography

3. Routine hematology and biochemistry

4. Culture and sensitivity

5. Endoscopy

6. Biopsy

7. Ultrasonography

8. Water quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Management

• Maintain optimum water quality.

• See Nursing Care.

Treatment/specific therapy

• Traumatic damage/loss of eye

• Consider antibiotic therapy.

• Remove aggressive individuals, sharp aquarium furniture, etc.

• Bacterial infections

• Antibiotics

• Fusarium mycosis: No effective treatment

• Ichthyophonus

• No effective treatment

• Enucleation

• Glaucoma

• Enucleation

• “Drop eye”

• Etiology unknown

• Likely to be a neurologic problem leading to loss of function of the muscles that control the eye, possibly as a result of head trauma while jumping

• Neoplasia

• Enucleation

• Euthanasia

• Cardiomyopathy—see Cardiovascular and Hematologic Disorders

• Nutritional disorders

• Feed analysis

• Correction with dietary supplements

Anorexia

Episodes of anorexia can occur, especially in large predatory fish. These may be associated with poor environmental conditions (incorrect water parameters, inadequate space, incorrect social or species mix), pathology including pharyngeal masses, foreign body or other physical obstructions, and physiologic factors such as reproductive status. Condition loss may be minimal to begin with.

1. Review and correct environmental conditions.

2. Review diet, including presentation—live foods may be required for reluctant predators to stimulate feeding behavior. For many predators, mimicking prey movement by impaling food items on a clear stick may work.

3. Gavage under heavy sedation or anesthesia (see "Anesthesia" in Chapter 14). Cat urinary catheters make suitable gavage tubes for smaller fish; larger fish will tolerate silicone tubing or similar. The esophagus of predatory fish is often short and distensible and is very amenable to tubing. Aim the tube toward the back of the pharynx—if deflected it will exit through one or other opercular opening. Give 2% to 4% body weight at intervals that are felt a suitable compromise between the stress of handling and anesthesia against the benefit of feeding. Regurgitation upon recovery can be a problem. In some cases gavage feeding may be needed for several weeks or even months.

4. Note that some cyprinids such as carp and goldfish do not have a distinct stomach, and care should be taken when gavaging to account for this.

Endocrine disorders

• Goiter in freshwater stingrays—see Endocrine Disorders in Chapter 16

Renal disorders

In many fish, the kidney is divided into two sections. The caudal pole excretes urine and, along with the gills, is important in osmoregulation. The other section is involved with hematopoiesis and immune function, including white blood cell production and antibody formation. The osmoregulatory function means that freshwater fish excrete prodigious amounts of dilute urine to eliminate the excess water entering across the skin and gills. Severe renal disease may result in severe osmoregulatory upset, with extreme cases developing into ascites.

Bacterial

• Nephritis

Fungal

Protozoal

• Myxozoans

Neoplasia

• Renal cyst adenomas (possibly genetic in red oscars, Astronotus occellatus)

Other noninfectious problems

• Prolonged exposure to free CO₂ levels >10 to 20 mg/L has been associated with nephrocalcinosis, mineral deposits forming in the renal tubules, collecting ducts, and ureters.

Findings on clinical examination

• Wasting and general malaise

• Anemia

• Ascites due to osmoregulatory disruption

• Mortalities

• Swollen abdomen

Investigations

1. Radiography

a. Swimbladder displacement (renal and other coelomic neoplasia)

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

7. Postmortem examination

8. Water quality parameters

a. Check temperature, ammonia, nitrite, nitrate, and pH values.

b. High CO₂ levels may be linked with low pH levels, high stocking densities, poor water circulation, and excess CO₂ infusion in planted aquaria.

TreatmentZspecific therapy

• CO₂ excess

• Assess possible underlying causes and correct (see Investigations 8b above).

• Neoplasia

• Surgical resection

• Euthanasia

Reproductive disorders

Fungal

• Ichthyophonus hoferi—see also Skin Disorders, Neurologic and Swimming Disorders, Ophthalmic Disorders, and Systemic Disorders

Protozoal

• Hexamita

Other noninfectious problems

• Functional sterility is seen in fancy strains of live-bearers (guppies, swordtails) where there is increased length or branching of the gonopodium—the modified anal fin used for sperm transfer in these fish. In these strains it is usually only young males without full gonopodial development that are used for breeding. In the guppy this is an autosomal dominant mutation, in which increased branching of the fins produces

a veil-tail appearance.

• Lethal gene in certain strains of black Siamese fighting fish (Betta splendens); such strains must be outcrossed to be propagated.

• Nicotine toxicity—see also Neurologic and Swimming Disorders

• Egg retention—see Reproductive Disorders in Chapter 14

• Dystocia in live-bearing species (e.g., freshwater stingrays)

Findings on clinical examination

• Poor reproductive performance in cichlids (Hexamita)

• Sex reversal in guppies (female to male); also lethargy, pale skin, protruding eyes (Ichthyophonus)

• Swollen body cavity (dystocia in stingrays)

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

a. Check for fetal heartbeats in dystocic stingrays.

7. Water-quality parameters: Check temperature, ammonia, nitrite, nitrate, and pH values.

Treatment/specific therapy

• Ichthyophonus: No treatment. Consider euthanasia.

• Hexamita

• See Gastrointestinal Tract Disorders.

• Nicotine toxicity—see also Neurologic and Swimming Disorders

• Dystocia

• If possible, calculate if over due date (in stingrays gestation is around 2.5 to 3 months; young females will have 1 to 2 young; older, full-sized females can have 8 or more).

• Under general anesthesia, assess if young are alive either by observation/palpation of young or ultrasonography.

• Young may be delivered per cloaca or via surgical salpingotomy.

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