Tropical marine fish

Changes in pigmentation

• Large discrete white spots, labored breathing, flashing (Cryptocaryon irritans, marine white spot)

• Fine white “dusting” on skin, labored breathing, flashing (Amyloodinium—coral fish disease, Crepidoodinium)

• Gray skin due to excessive mucus production, reddened skin, ulceration (skin flukes, ectoparasites)

• Hemorrhages, ulceration, abnormal swimming, shimmying (bacterial disease)

• Small black spots over body, cloudy skin, respiratory distress, especially in laterally compressed fish such as yellow tangs (Zebrasoma flavescens, Turbellaria)

• Fingerprint-like marks on skin of tangs and surgeonfish (tang fingerprint disease virus)

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

• Light gray patches that are multifocal, well defined, and ovoid in blacktip sharks (Carcharinus limbatus)—Dermopthirus; see Bullard et al 2000

Ectoparasites

• Protozoa

• Cryptocaryon irritans—see also Respiratory Tract Disorders

• Amyloodinium and Crepidoodinium—see also Respiratory Tract Disorders

• Brooklynella hostilis—see also Respiratory Tract Disorders

• Uronema marinum—see also Respiratory Tract Disorders

• Miamiensis marinum, especially seahorses

• Turbellaria—see also Respiratory Tract Disorders

• Microsporidians (e.g., Glugea, Pleistophora, Sprauga spp.)

• Helminths

• Skin flukes (Gyrodactylus)

• Gill flukes (dactylogyrids—see also Respiratory Tract Disorders)

• Dermopthirius penneri

• Crustacea

• Livoneca

• Lerneascus spp.

Neoplasia

• Nonsymmetrical swelling, ulceration, loss of balance

• Epithelioma

• Papillomas

Investigations

1. Skin scrape and light microscopy

a. Protozoa

i. Brooklynella: Large (55 to 85 μm) and mobile ciliates, with the basket-shaped “mouth” and cilia very apparent

ii. Cryptocaryon: Large (48 ? 27 to 450 ? 350 μm) oval-shaped ciliated protozoa with a characteristic four-lobed nucleus

iii. Amyloodinium: Can be quite large, up to 1.0-mm diameter, oval-shaped with a very dark appearance because of chloroplasts; not usually mobile

iv.

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. 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 as a minimum: temperature, ammonia, nitrite, nitrate, and pH values.

TreatmentZspecific therapy

• Gas bubble disease—see also “Seahorse Gas Bubble Disease” in Systemic Disorders

• Oxygen supersaturation usually secondary to pressurized oxygenation

(e.g., malfunctioning Venturi pumps), excess photosynthesis (high algae levels)

• Correct source of problem

• Rarely fatal—fish usually recover uneventfully

• HLLD

• No treatment for aquareovirus

• Vitamin A supplementation, either in commercial supplement or as “greens” (e.g., suchi seaweed wraps)

• Metronidazole at 50 mg/kg PO per day if suspect protozoal involvement

• Tiger puffer virus

• No treatment available. Supportive care only

• Tang fingerprint disease virus

• No treatment available. Supportive care only

• Lymphocystis

• No direct cure; usually self-limiting

• Ozone or ultraviolet sterilization may reduce spread.

• Attempted surgical removal is usually followed by recurrence.

• Epitheliocystis

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

• Bacterial infections

• Antibiotics

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

• Nocardia and mycobacteriosis

• Antibiotic treatment not very effective

• Consider euthanasia, especially because of zoonotic risk.

• Exophthaliosis

• Ketoconazole at 5.0 mg/kg PO s.i.d.

• Itraconazole at 1 to 10 mg/kg PO. (in feed) s.i.d. for 1 to 7 days

• Ichthyophonus hoferi

• No efficacious treatment available. Try treatment as for Exophthaliosis, above.

• Glugea

• No effective treatment. Consider:

- Toltrazuril at 30 mg/L bath for 60 minutes repeated every other day for 3 treatments

- Feeding a diet of 0.1% fumagillin

• Myxosporidea

• No effective treatment—try as for Glugea above

• Cryptocaryon irritans—marine white spot

• Sensitive to copper-based ectoparasitic treatments (see Nursing Care, above)

• Formalin baths

• Freshwater dips

• Cryptocaryon tomonts cannot survive at salinities with a specific gravity below around 1.015 (a salinity of around 16 ppt). Maintaining Cryptocaryon-infested fish at 1.015 or below for a minimum of 6 days can effect a cure at standard tropical temperatures. Examples of fish groups able to adapt to such low levels of salt include the blennies (Blennidae), groupers (Serranidae), target fish (Theraponidae), jacks (Carangidae), snappers (Lutja), rabbitfishes (Siganidae), damselfish and clownfish (Pomacentridae), left-eye flounders (Bothidae), and even some marine angelfish (Pomacanthids). Estuarine and rock pool fish will also have little difficulty osmoregulating at such low salinities. Some invertebrates such as cleaner shrimps (Lysmata spp.) may well not survive such treatment.

• Amyloodinium and Crepidoodinium

• Sensitive to copper-based ectoparasitic treatments

• The encysted stage is relatively resistant to chemical attack.

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

• In such cases, treat with metronidazole at 50 mg/L daily for 10 days, changing the water daily.

• 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.

• Brooklynella, Uronema, and Miamiensis

• Sensitive to proprietary formalin/malachite green and/or copper-based ectoparasitic treatments

• Freshwater baths for larger/tougher fish

• Covering antibiosis

• Skin flukes

• Proprietary ectoparasitic preparations

• Praziquantel at 10 mg/L for a 3-hour bath, or in feed at a rate of 400 mg/100 g food daily for 7 days (but see Neurologic and Swimming Disorders)

• Freshwater dips 5 minutes once daily for 5 days

• Dermophthirius penneri

• Consider praziquantel as above.

• Turbellaria

• Formalin bath at 2 mL/L for up to 1 hour

• 5-minute freshwater bath daily for 5 days

• Crustacean ectoparasites

• Individual removal of parasites

• Treat with lufenuron (Program, Novartis) at 0.088-0.13 mg/L as a once-only treatment.

• Treat with organophosphates if legal to do so.

• Neoplasia

• Surgery or euthanasia

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

Respiratory tract disorders

Bacterial

• Bacterial gill disease, especially Flavobacteria (sygnathids)

• Epitheliocystis (sygnathids)

Fungal

• Fungal gill disease

Protozoal

• Cryptocaryon irritans—see also Skin Disorders

• Amyloodinium and Crepidoodinium—see also Skin Disorders

• Brooklynella hostilis—see also Skin Disorders

• Uronema marinum—see also Skin Disorders

• Miamiensis marinum, especially seahorses

• Turbellaria—see also Skin Disorders

• Coccomyxa hoffmani (Myxosporidean)

Parasitic

• Gill flukes (Dactylogyrus, Microcotyle, Haliotrema, Ancyrocephalus, Pseudoancyrocephalus, Cleithrarticus, Neohaliotrema, and Pseudempleurosoma)

Neoplasia

Other noninfectious problems

• Hypoxia

• Ammonia toxicity—see also Neurologic and Swimming Disorders

• Copper toxicity

Findings on clinical examination

• Moderate to extreme respiratory effort

• Rapid gill ventilation

• Apparent gasping at water surface

• Abnormal color of gills, necrosis, exposure of underlying cartilage

• Respiratory distress, irritation, ulceration (Brooklynella, Uronema)

• Respiratory distress, small black spots over body with cloudy skin (Turbellaria)

• Respiratory distress, clamped fins, scratching and flashing, inactivity (gill flukes)

• Gill or intraoral mass

Investigations

1.

a. Protozoa

i. Brooklynella: Large (55 to 85 μm) and mobile ciliates, with the basket-shaped “mouth” and cilia very apparent

ii. Cryptocaryon: Large (48 ? 27 to 450 ? 350 μm) oval-shaped ciliated protozoa with a characteristic four-lobed nucleus

iii. Amyloodinium: Can be quite large, up to 1.0-mm diameter, oval-shaped with a very dark appearance because of chloroplasts; not usually mobile

iv. Uronema and Miamiensis: Motile, oval-shaped protozoan parasites

v. Coccomyxa hoffmani: Cartilage of the gill filaments of coral catfish (Plotosus anguillaris)

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

2. Radiography

3. Routine hematology and biochemistry

4. Culture and sensitivity

5. Endoscopy

6. Biopsy

7. Ultrasonography

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

Management

• Good oxygenation of water; recommended level of oxygen is above 5.5 mg/L at 25° C for tropical marine fish.

TreatmentZspecific therapy

• Ammonia toxicity

• Partial water changes to dilute the ammonia levels

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

• Bacterial gill disease

• Correct any underlying environmental problem.

• Chloramine-T at 5 to 10 mg/L

• Appropriate antibiosis

• Epitheliocystis

• Chlamydophila-like organism

• Considered nonpathogenic in sygnathids

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

• Fungal gill disease

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

• Brooklynella, Uronema, and Miamiensis

• Sensitive to proprietary formalin/malachite green and/or copper-based ectoparasitic treatments

• Freshwater baths for larger/tougher fish

• Covering antibiosis

• Cryptocaryon irritans (marine white spot)

• Sensitive to copper-based ectoparasitic treatments (see Nursing Care above)

• Formalin baths

• Freshwater dips

• Amyloodinium and Crepidoodinium

• Sensitive to copper-based ectoparasitic treatments (see Nursing Care above)

• The encysted stage is relatively resistant to chemical attack.

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

• In such cases, treat with metronidazole added to water at 50 mg/L daily for 10 days, changing the water daily.

• 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.

• Turbellaria

• Formalin bath at 2 mL/L for up to 1 hour

• 5-minute freshwater bath daily for 5 days

• Gill flukes

• Proprietary ectoparasitic preparations

• Praziquantel at 10 mg/L for a 3-hour bath or in feed at a rate of 400 mg/100 g food daily for 7 days (but see Neurologic and Swimming Disorders)

• Freshwater dips 5 minutes daily for 5 days

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

• Coccomyxa hoffmani

• No treatment

• Copper toxicity

• Multiple partial water changes

• See also Nursing Care above.

• Neoplasia

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

• Euthanasia if inoperable

Gastrointestinal tract disorders

Bacterial

• Vibrio parahaemolyticus (Oestmann 1985)

Protozoal

• Cryptosporidium (tangs, sygnathids)

• Eimeria sygnathi and E. phillopterycis (sygnathids)

Parasitic

• Tapeworms

• Tetraphyllidea

• Spathebothriidea

• Trypanorhyncha

• Pseudophyllidea

• Nematodes

• Spirocamallanus

• Cucullanus

• Camallanus

Nutritional

• Inappropriate feeding

Neoplasia

• Intestinal carcinoma in sygnathids (LePage et al 2014)

Other noninfectious problems

• Overgrowth of incisor teeth in pufferfish, parrotfish, and trigger fish

• Foreign body

• Air ingestion by neonatal seahorses

Findings on clinical examination

• Weight loss, poor growth, swollen abdomen (tapeworms)

• A cluster of worms protruding from the anus of an infested fish often accompanied by extensive damage and erosion around this area (Spirocamallanus); also weight loss, failure to thrive, stringy or slimy feces, and a susceptibility to secondary infections, including tail and fin rot

• Weight loss, regurgitation, undigested food in feces, and anorexia in tangs (Cryptosporidium)

• Chronic weight loss in pufferfish, triggerfish, or parrotfish; appetite still good, difficulty feeding (incisor overgrowth)

• Hemorrhagic feces, reddening around cloaca; also erythematous skin lesions and boil-like lesions following septicemia (Vibrio parahaemolyticus)

• Swollen coelom, lethargy (foreign body, inappropriate nutrition, neoplasia, egg retention—see Reproductive Disorders)

• Neonatal seahorses with gas bubbles visible in their guts; trapped floating at surface

Investigations

1. Fecal examination

2. Anesthetize and examine teeth/buccal cavity

3. Radiography

4. Routine hematology and biochemistry

5. Culture and sensitivity

6. Endoscopy

7. Biopsy

8. Ultrasonography

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

Treatment/specific therapy

• Vibrio parahaemolyticus

• Antibiotics

• Quarantining/removal of infected fish

• Cryptosporidium nasoris—no effective treatment

• Tapeworms

• Praziquantel at 10 mg/L for a 3-hour bath (but see Neurologic and Swimming Disorders)

• Cucullanus, Camallanus, and Spirocamallanus

• Levamisole at 10 mg/L as a single dose added to the water. This is particularly good for killing larval worms. Suspend carbon filtration.

• Piperazine at 2.5 mg/g of feed, added to the food. This may only kill adult worms.

• Fenbendazole at 50 mg/kg body weight added to feed, or by stomach tube if the fish is large enough. Fish are quick to refuse medicated food, so it is best to starve for 24 to 48 hours prior to offering such feed.

• 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).

• Inappropriate nutrition

• Some marine fish fed on foods designed for other fish (e.g., koi foods) can develop a gastric or intestinal bloat and ileus as a result of excessive carbohydrate intake.

• Starve for 24 to 48 hours.

• Gavage activated charcoal.

• Covering antibiosis

• Neoplasia

• Surgical resection

• Air ingestion in neonatal seahorses

• Neonatal seahorses are often fed on Artemia nauplii (brine shrimp); these larvae are positively phototactic and accumulate at the surface where the light intensity is strongest. Neonatal seahorses accidentally ingest air at the surface while feeding.

• Cover the surface so as to darken it and light from below and to the side to attract the Artemia (and so the neonates) away from the surface.

• Foreign body

• Retrieval from stomach, possibly with aid of endoscopy

• Coeliotomy and surgical retrieval

Nutritional disorders

• Hypovitaminosis A

• Suggested as a cause of HLLD in marine angelfish and tangs (see Skin Disorders)

• Provide either with a commercial vitamin A supplement or offer more vegetable foods (e.g., suchi mori seaweed wraps or lightly boiled greens)

• Highly unsaturated fatty acid (HUFA) deficiency

• Commonly seen in captive-bred marine fry (e.g., clownfish, Amphiprion spp.) fed wholly or largely on unsupplemented brine shrimp Artemia nauplii. Jerky spasmic swimming and mass deaths are often triggered by external stimuli such as a loud noise or water change.

• Supplement with commercially available HUFA products.

• Hepatic lipidosis

• Frequently seen in large predatory species such as groupers (Serranidae) and lionfish (Pterois spp.) that are overfed; often exacerbated by the feeding of freshwater fish such as goldfish that are deficient in HUFA

• Failure to provide appropriate foods

Note: Many marine fish are specialist feeders. Those that prey primarily on coral polyps such as the exquisite butterflyfish (Chaetodon austriacus) or sponges (such as the rock beauty Holocanthus tricolor) may receive inadequate diets and fail to thrive.

• Underfeeding

• Some aquarists may deliberately underfeed to reduce the levels of metabolites in reef systems.

• Overfeeding

• In addition to hepatic lipidosis and other obesity-related problems, overfeeding can cause rapid and dangerous changes in the water quality, particularly triggering falls in the pH and KH.

Findings on clinical examination

• Weight loss

• Inappetence

• Lethargy

• Mass mortality of larvae or fry (HUFA insufficiency)

• Ulcerative lesions on the head and lateral line of marine angelfish, surgeonfish, and tangs

Investigations

1. Review species identification and husbandry.

2. Radiography

3. Routine hematology and biochemistry

4. Culture and sensitivity

5. Endoscopy

6. Biopsy

7. Ultrasonography

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

9. Postmortem

a. Lack of food in stomach/intestines

b. Loss of body fat

Treatment/specific therapy

• Address obvious deficiencies.

• Otherwise as described above

Hepatic disorders

Bacterial

• Hepatitis

Fungal

• Hepatitis

Protozoal

• Myxosporideans (e.g., Ceratomyxa, Myxidium, Leptotheca, and Sphaeromyxa spp.)

Nutritional

• Hepatic lipidosis (see Nutritional Disorders)

Neoplasia

• Liver neoplasia

Findings on clinical examination

• Weight loss

• Inappetence

• Lethargy

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

a. Histopathology

i. Myxosporideans in the gallbladder. Large numbers may affect function of gallbladder

ii. Sphaeromyxa spores in the gallbladder of seahorses (Hippocampus spp.—Vincent and Clifton-Hadley 1989)

6. Ultrasonography

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

Treatment/specific therapy

• Myxosporideans

• No treatment. Usually an incidental finding

• Bacterial and fungal hepatitis

• Treat as for similar infections in Systemic Disorders.

Pancreatic disorders

Viral

• Infectious pancreatic necrosis virus—see Systemic Disorders

Neoplasia

• Exocrine pancreatic carcinoma in sygnathids (LePage et al 2014)

Cardiovascular and hematologic disorders

Bacterial

• Endocarditis

Protozoal

• Hemoparasites (e.g., Trypanosoma, Trypanoplasma, Haemogrergarina spp.—see Systemic Disorders

Neoplasia

• Mesothelioma (Shields and Popp 1979)

• Cardiac rhabdomyosarcoma in sygnathids (LePage et al 2014)

Other noninfectious problems

• Cardiomyopathy

Findings on clinical examination

• Anemia, abnormal swellings (Trypanoplasma spp.)

• Lethargy

• Anorexia

• Nonspecific signs of ill health

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

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

TreatmentZspecific therapy

• Hemoparasites

• Try methylene blue at 60 mg/kg per day PO for 4 days.

• Metronidazole at 50 mg/kg PO per day

• Bacterial endocarditis

• Likely to be diagnosed on postmortem

• Appropriate antibiosis

• Cardiomyopathy

• Likely to be diagnosed on postmortem

Systemic disorders

Viral

• Infectious pancreatic necrosis virus

• Angelfish encephalitis virus (Pomacanthus, Holocanthus, and Centropyge spp.—see also Neurologic and Swimming Disorders)

• Banggai cardinal iridovirus (BCIV; megalocytivirus) in Banggai cardinalfish (Pterapogon kauderni)

Bacterial

• Abnormal swimming, shimmying; may also see hemorrhages, ulceration (bacteremia, septicemia)

• Mycobacteria, especially M. marinum, M. fortuitum, and M. cheloni (fish tuberculosis), especially seahorses (Hippocampus spp.—see also Skin Disorders and Musculoskeletal Disorders)

• Nocardia asteroides

• Renibacterium (Corynebacterium) spp.

Fungal

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

Protozoal

• Hemoparasites—see Cardiovascular and Hematologic Disorders

Neoplasia

Other noninfectious problems

• Sudden-onset water quality toxicity; new tank syndrome

• Pouch and systemic emphysema of male seahorses (seahorse gas bubble disease)

• Cyanide toxicity (in recently caught wild marine fish)

Findings on clinical examination

• Sudden darting movements, loss of balance, rapid respiration (poor water quality)

• Anorexia, lethargy, abdominal fluid accumulation, sudden death (infectious pancreatic necrosis virus)

• Weight loss, thickened areas of inflammation, ulceration, fin rot (Nocardiosis, mycobacteriosis)

• Loss of balance in male seahorses (Hippocampus spp.) accompanied by obviously swollen brood pouch. May float at surface. Emboli may also be found subcutaneously, especially at the tail (Fig. 16-2) (seahorse gas bubble disease)

• Weakness, wasting, and anemia (hemoparasites)

• Lethargy, weight loss, excessive mucus production, loss of balance, and death in marine angelfish (angelfish encephalitis virus)

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

• Swollen abdomen, ascites (Renibacterium spp.)

Fig 16-2. Seahorse with systemic emphysema affecting the tail. Note how the tail floats at the surface.

• Anorexia, excessive bright colors, deaths in recently caught fish (cyanide toxicity)

• Banggai cardinalfish: lethargy, darkening of body pigmentation, inappetence, listlessness, increased respiratory rate, white fecal casts, mortalities within 2 days; often mass mortalities (BCIV)

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

7. Histopathology (BCIV)

8. Assay for cyanide on postmortem

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

TreatmentZspecific therapy

• Water quality problem

• Identify and address problem.

• Infectious pancreatic necrosis virus: No treatment. Supportive only

• BCIV: No treatment. Isolate and euthanize to confirm diagnosis and prevent transfer to other Banggai cardinalfish.

• Angelfish encephalitis virus: No treatment. Supportive only

• Bacterial disease (bacteremia, septicemia)

• Antibiotics

• Nocardiosis—see Skin Disorders

• Mycobacteriosis—see Musculoskeletal Disorders

• Ichthyophonus hoferi: No efficacious treatment available

• Hemoparasites

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

• Metronidazole at 50 mg/kg PO per day

• Seahorse gas bubble disease (pouch and systemic emphysema of male seahorses)

• Unknown etiology—often linked to subclinical mycobacteriosis, metabolic disturbances, and occasionally brood pouch infections

• Gently release trapped air from brood pouch. For systemic emphysema aspirate gas from obvious gas pockets.

• Acetazolamide. Three treatment options:

- 2 to 3 mg/kg IM every 5 to 7 days for up to 3 treatments

- Flush the brood pouch with an acetazolamide solution daily for 3 days.

- 2 to 4 mg/L as a 24-hour treatment over 3 consecutive days. Perform a 100% water change between treatments. Note: Acetazolamide may temporarily affect both vision (Fairbanks et al 1974) and balance (Beier et al 2002), potentially giving rise to apparent inappetence.

• High-pressure treatment (exposing affected seahorses to great depth) has been successful in curing this condition.

• Antibiotics if appropriate

• In H. erectus, incidence of seahorse gas bubble disease was lowest at 26° C rather than 23° C, which may support a metabolic etiology (Lin et al 2010). Therefore, reassess environmental parameters, including preferred temperature range.

• Cyanide toxicity

• No effective treatment—supportive therapy only

Musculoskeletal disorders

Bacterial

• Mycobacteria, especially M. marinum, M. fortuitum, and M. cheloni (fish tuberculosis—see also Skin Disorders and Systemic Disorders)

Parasitic

• Tapeworms—see Gastrointestinal Tract Disorders

Neoplasia

Other noninfectious problems

• Electrocution (Pasnik et al 2003)

• Idiopathic myopathy of seahorses (H. kuda)—LePage et al 2014)

Findings on clinical examination

• Spinal curvature, ulceration, weight loss (mycobacteriosis, electrocution)

• Chronic weight loss, skin ulceration (mycobacteriosis)

• Weight loss (mycobacteriosis, tapeworms)

• Sudden multiple mortalities (electrocution)

Investigations

1. Check electrical equipment for faults.

2. Radiography

a. Vertebral fractures (electric shock)

3. Routine hematology and biochemistry

4. Culture and sensitivity

5. Endoscopy

6. Biopsy

7. Ultrasonography

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

TreatmentZspecific therapy

• Mycobacteriosis

• Antibiotic treatment not very effective

• Kanamycin 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.

• Electrocution

• No specific treatment

Neurologic and swimming disorders

Viral

• Angelfish encephalitis rhabdovirus (Pomacanthus, Holocanthus, and Centropyge spp.—see also Systemic Disorders)

Bacterial

• CNS infection/granuloma

• Eubacterium tarantellus

Fungal

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

• Central nervous system infection/granuloma

Protozoal

• Septemcapsula plotosi (Myxosporidea) in coral catfish (Plotosus anguillaris)

Nutritional

• HUFA deficiency—see Nutritional Disorders

Neoplasia

Other noninfectious problems

• Sudden-onset water quality problem; new tank syndrome

• Ammonia toxicity—see also Respiratory Tract Disorders

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

• Swimbladder torsion

• Praziquantel toxicity

• Nicotine toxicity

• Heavy metal poisoning

Findings on clinical examination

• Sudden darting movements, loss of balance, rapid respiration (water quality problem)

• Lethargy, weight loss, excessive mucus production, loss of balance, and death in marine angelfish (angelfish encephalitis virus)

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

• Spasmic, jerky swimming movements accompanied by sudden mass deaths in captive- bred marine fish (e.g., clownfish) fed wholely or largely on brine shrimp Artemia nauplii (Ω-3-fatty acid deficiency)

• Whirling behavior, death in coral catfish (Septemcapsula)

• Stiffened pectoral fins, muscular spasms (nicotine toxicity)

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

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

Treatment/specific therapy

• Water quality problem

• Identify and address problem.

• Ammonia toxicity

- Partial water changes to dilute the ammonia levels

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

• Angelfish encephalitis rhabdovirus: No treatment. Supportive only

• Ichthyophonus hoferi: No efficacious treatment available

• Swimbladder torsion

• Surgical correction

• CNS infection/granuloma

• Attempt antibiotic or antimycotic treatment. Poor prognosis

• Eubacterium tarantellus

• Antibiotic therapy

• Septemcapsula plotosi

• No effective treatment

• Praziquantel toxicity

• Terminate treatment.

• Nicotine toxicity

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

• Heavy metal poisoning

• Partial water changes

• Remove possible sources (e.g., piping, equipment not designed for marine aquaria, such as central heating pumps).

Ophthalmic disorders

Bacterial

• Bacterial granuloma

• Uveitis

Fungal

• Fungal granuloma

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

• Uveitis

Protozoal

• Cryptocaryon

• Henneguya

Nutritional

• Lipid keratopathy (in green moray eels; see Greenwell and Vainisi 1994)

• Riboflavin deficiency

• Ascorbic acid deficiency

• Hypovitaminosis A

Neoplasia

• Thyroid neoplasia

• Lymphoma

Other noninfectious problems

• Blindness secondary to exposure to excessive bright light in nocturnal species, especially lionfish (Pterois and Dendrochirus spp.)

• Gas bubble disease—see also Skin Disorders, Reproductive Disorders, and Systemic Disorders

• Trauma (Carrillo et al 1999)

• Cardiomyopathy

Findings on clinical examination

• Blindness (may present as inability to locate food in predatory species)

• Cataracts

• Exophthalmos

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

• Glaucoma, usually secondary to intraocular disease

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

Investigations

1. Ophthalmic examination (under sedation/general anesthesia)

2. Radiography

3. Routine hematology and biochemistry

4. Culture and sensitivity

5. Endoscopy

6. Biopsy

7. Ultrasonography

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

TreatmentZspecific therapy

• Bacterial or fungal uveitis

• Appropriate antibiosis

• Enucleation

• Gas bubble disease

• If only eyes affected (frequently in seahorses), consider acetazolamide:

- 2 to 3 mg/kg IM every 5 to 7 days for up to 3 treatments

- 2 to 4 mg/L as a 24-hour treatment over 3 consecutive days. Perform a 100% water change between treatments. Note: Acetazolamide may temporarily affect vision, giving rise to apparent inappetence.

• Species other than seahorses: Likely to be connected to supersaturation of water—see Skin Disorders

• Blindness secondary to excessive exposure to bright light

• Reduce lighting levels.

• Supplement with vitamin A.

• Ichthyophonus hoferi

• No efficacious treatment available

• Glaucoma

• Enucleation

• Lipid keratopathy

• Keratoplasty; see Greenwell and Vainisi 1994

Anorexia

See “Anorexia” in Chapter 15.

Endocrine disorders

Neoplasia

• Thyroid adenoma

• Thyroid adenocarcinoma (Blasiola et al 1981)

Other noninfectious problems

• Goiter (hypothyroidism) in marine elasmobranchs

Findings on clinical examination

• Swelling in the thyroid region (especially visible in sharks and rays)

Investigations

1. Radiography

2. Routine hematology and biochemistry

a. Blood thyroid levels (Table 16-4)

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

7. Water quality parameters

a. Check as a minimum: Temperature, ammonia, nitrite, nitrate, and pH values.

b. High nitrate levels antagonize iodine uptake.

TreatmentZspecific therapy

• Goiter

• Supplement with dietary iodine at 20 pg/kg PO or IM every 48 hours.

• Reduce nitrate levels to below 40 mg/L, preferably below 10 mg/L.

• Thyroid adenoma

• May require surgery but likely to be technically very difficult.

Urinary disorders

Bacterial

• Renibacterium spp. (Corynebacterium)

Fungal

Protozoal

• Myxosporidea

Neoplasia

• Renal adenoma, renal adenocarcinoma, renal round cell tumor in sygnathids (LePage et al 2014)

Other noninfectious problems

Findings on clinical examination

• Swollen body, ascites (Renibacterium spp.)

• Nonspecific signs of ill health, including anorexia and lethargy

Investigations

1. Radiography

2. Routine hematology and biochemistry

3. Culture and sensitivity

4. Endoscopy

5. Biopsy

6. Ultrasonography

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

TreatmentZspecific therapy

• Renibacterium

• Appropriate antibiosis

• Reduce salinity to 1.020 to reduce osmotic stress.

• Myxosporidea

• No effective treatment, but see Skin Disorders

Reproductive disorders

See Reproductive Disorders in Chapters 14 and 15.

Noninfectious problems

• Pouch emphysema of seahorses—see Systemic Disorders

• Egg retention—see Reproductive Disorders in Chapters 14 and 15.

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