Diseases in the Aquarium - Part V
A nearly complete guide to Fish Diseases

An Article by George J. Reclos

Nodular diseases
DISEASE Caused by various microsporidian and myxosporidian parasites such as Ichthyosporidium, Nosema, Myxobolus and Henneguya and the fungus Dermocystidium.
SYMPTOMS Small to large smooth, yellowish white cysts on skin, fins, gills, in muscle or among internal organs. Size of cysts varied from a few millimeters to a centimeter. Usually spherical or oval although some may be elongated or irregularly shaped.
TREATMENT None reliable treatment.
PREVENTION Isolate and treat infected fish separately. Disinfect tanks and all equipment which have contained infected fish. Do not buy obviously infected fish.

Nutritional problems
Nutritional problems refer to vitamin deficiencies
SYMPTOMS Vary according to the vitamin which causes the deficiency. Symptoms may be identical to symptoms observed in other diseases (lethargy, cloudy eyes etc).  Some common symptoms in Vitamin deficiencies are:

  • Vitamin A : Poor growth, loss of appetite, eye problems, dropsy, gill problems, hemorrhage at fin base.

  • Vitamin B1 (Thiamine) : Poor appetite, muscular wasting, convulsions, loss of equilibrium, edema, poor growth,

  • Vitamin B2 (Riboflavin) : Cloudy eyes, blood shot eyes, poor vision, avoidance reaction to light (photophobia), dark coloration, poor appetite, poor growth, anemia.

  • Vitamin B6 (Pyridoxine) : Nervous disorders, loss of appetite, anemia, edema, gasping, flaring of gill covers.

  • Vitamin B12 (Cyanocobalamine) : Poor appetite, anemia, poor growth.

  • Biotin : Loss of appetite, poor growth, muscular wasting, convulsions, skin and gut lesions.

  • Choline : Poor growth, visceral hemorrhages.

  • Folic acid : Poor growth, lethargy, fin damage, dark coloration, anemia.

  • Inositol : Poor growth, dropsy, skin lesions.

  • Pantothenic acid : Gill and skin problems, loss of appetite, poor growth, lethargy.

  • Vitamin C : Dark coloration, skin problems, eye diseases, spinal deformities.

TREATMENT Supplement the missing vitamin.
PREVENTION Feed a variety of commercially available brand foods of good quality

Oodinium (velvet)
DISEASE OODINIASIS (="OODINIUM" = "VELVET" DISEASE) - caused by protozoan dinoflagellates (Oodinium Limneticum in freshwater - Oodinium ocellatum in saltwater). Almost always caused by exposing fishes to high levels of ammonia / nitrite poisons, e.g. during intercontinental shipment, immature filtration systems etc.
SYMPTOMS Within 6-8 hours of the fish becoming infected the respiratory rate rises very steeply from the normal 60-90 GB/min. to as high as 200-300 GB/min. If not treated quickly at this stage, tiny grayish-fawn cysts (difficult to spot with naked eye unless fish can be maneuvered into a head on position with light behind it) appear in enormous numbers on body and finnage. Can never be confused with "white-spot" disease since - a) the spots are much smaller, and b) "white-spot" disease doesn't cause an increase in respiratory rate until several untreated days have passed and the fish is dying. Some species occasionally seen to flick and twitch pelvic / dorsal fins and even close down the worst-infected gill chamber if disease progress untreated.
TREATMENT Carry out 25%-33% partial water change if time permits and repeat changes at very close intervals (even twice daily) until respiratory rate falls to a normal 60-90 GB/min. Stop all feeding until symptoms disappear. Treat with a proprietary velvet remedy, white spot remedy or a broad spectrum antiparasite treatment (copper sulphate ; 0.15-0.30 mg/Liter - continuous bath for up to four weeks and / or metronidazole; 7mg/litre - continuous bath, may need repeating). Badly affected fish should be isolated and treated separately. The speed at which this infestation spreads and the severity of the problems it may cause highlight the importance of quarantine and a preventive course (e.g. with copper sulphate).
PREVENTION Never permit the nitrite reading to show higher than 0.125ppm (=1/8 mg/liter). This means using an efficient filtration system. Never permit nitrate reading to climb higher than minimum permissible level indicated on the test kit literature. Never overfeed.. Never use seafoods, Daphnia, Tubifex, bloodworms etc., which are not gamma irradiated. Use plant supplements to promote vigorous, harvestable plant growth, or - conscientiously use partial water changes to control nitrate build up. This disease is extremely virulent and must be treated as soon as possible. The casual pathogens in both freshwater and saltwater aquariums are essentially gill parasites - hence the sudden and dramatic increase in respiratory rate.

Pop eye disease (exophthalmia)

A badly infected eye of a sub adult Fossorochromis rostratus which appeared to spread to other fish in the tank. Photo courtesy: Frank Panis. 

DISEASE Caused by a variety of factors including bacterial infection, parasite infestation, poor water quality and internal (metabolic) disorders.
SYMPTOMS One or both eyes protrude from the head in an unusual fashion.
TREATMENT It may be necessary to isolate the infected fish and treat it with a broad spectrum antibiotic (preferably by injection). However this will be effective only if the symptoms are related to a bacterial infection. Since this disease is usually characterized by low infectivity, it may be best to leave the affected fish in the main tank and provide it with good food and optimal conditions. If the disease appears to spread to previously unaffected stock remove the fish. Sometimes the protruding eye, especially if the original cause was physical damage - a common result from fighting, may protrude very much and at last fall. In this case, add a general antibacterial remedy in the water tank (to avoid secondary infections) and leave the fish as is. Usually, after a month, the would will heal and the fish will behave normally - even spawn.

Red sores
DISEASE FUNGUS, caused by Saprolegnia sps. fungi, poor hygiene, overfeeding and low temperatures.
SYMPTOMS Grayish-white, cotton-wool-like threads growing from the fish's body and particles of uneaten food, etc., on gravel.
TREATMENT Remove waste food from tank. Treat water with available aquarium antibacterial and antifungal agents.
PREVENTION These diseases are extremely difficult to treat - no doubt due to the facts that:
a) they are essentially diseases of the internal organs i.e. spleen, brain, liver, etc., which are difficult to reach with medications (at effective concentrations), and,
b) apart from Saprolegnia, there are no easily-seen external symptoms until the disease is already well advanced.

The key to successful avoidance however is undoubtedly keeping the system scrupulously clean at all times. Never overfeed, use the Nitrate, Nitrite, Ammonia, pH and Hardness test kits to ensure that water management, and water chemistry are always maintained within optimal limits. In short - keep stress to a minimum so that the time bomb ticks quietly away until your fishes cheat it by dying of old age.

Saprolegnia (See Fin and Tail rot - fungus)
Secondary infections
DISEASE - Caused by any pathogen.
SYMPTOMS Very difficult to distinguish since the symptoms of the primary disease and those of the secondary infection are present at the same time.
TREATMENT Usually you have to take the risk and treat the one which seems more life threatening for the fish.
PREVENTION Good hygiene, prime conditions of the fish, early diagnosis and treatment of the primary disease.

DISEASE It is caused by a broad spectrum invasion by numerous pathogens, protozoan, bacterial and fungal may be responsible.
SYMPTOMS Fishes (mostly livebearers and particularly Mollies) swim with curious shimmying action of body. Later, if untreated, fish becomes unable to swim and sit on the gravel listlessly shimmying.
TREATMENT Remove fish. Increase temp. To 27°C (85°F) Use a broad spectrum antibiotic or proprietary brand remedy.
PREVENTION Always maintain water chemistry in a livebearer tank in the following condition - high pH value (7.8 - 8.3pH), high hardness (15°DH+), high alkalinity. The best way of creating this livebearer (and Mbuna) special water, is to add up to 25% of seawater to the aquarium. Please remember to prepare replacement water in the same way. Never buy unmedicated, newly imported fishes.

Continued in next page  - you may also click to the following link for a List of medication products by leading manufacturers

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