Catfish Diseases Causes and Cure
First of all it must be made clear that African catfish is a very though fish species, with a very high resistance to infections. If African catfish does develop a disease, almost always the reason for the disease is related to environmental or management problems. Off course a disease in African catfish has to be treated properly, but in the mean time work on solving the cause of the problem in a structural way.
Some signs of African catfish diseases are easily shown:
The behaviour is abnormalAbnormalities on the fish, such as barbels decreasing in size, red spots or ulcers on the skin, open belly, swollen head kidneyBacterial infections (almost always caused by gram negative bacteria like Aeromonas sp.) can be treated after proper diagnosis (antibiogram) with antibiotics like Oxytetracycline and Trimethasulfmix. The supplier of the antibiotics should be assisting the farmer with the treatment. In most countries the supplier is a veterenarian specialized on fish diseases. Applying the right dosage of the drug to the African catfish is one of the problems I have encountered in Africa. Due to a lack of knowledge the antibiotics are used in too low dosages giving no direct effect to the diseased fish, but inducing resistance against the drug used in the pathogens. An African catfish hatchery should have the most common antibiotics in stock and should have the treatment procedures ready before any problem arise.
The Major Diseases and Control Measures
African catfish are subject to a wide variety of diseases including bacteria, fungi and miscellaneous parasites. Some of the most important disease organisms are included in the table below, though many of the observed diseases are yet to be fully diagnosed.
In some cases antibiotics and other pharmaceuticals have been used in treatment but their inclusion in this table does not imply an FAO recommendation.
DISEASE: Broken head AGENT: Unknown SYNDROME Skeletal deformities (lardosis and scoliosis); fish suddenly stop feeding, become lethargic and die with swollen weak tissues on both sides of the head; usually observed on fish >10 cm; dead fish exhibit thick and curved skulls testifying former lateral crack. MEASURES: Provide supplemental Vitamin C in feeds
DISEASE: Ruptured intestine syndrome AGENT: Unknown SYNDROME Lethargic behaviour; swollen abdomen; discoloured abdominal skin; reddish anal area; rupture of the abdominal wall at the final stage MEASURES: Provide sufficient balanced and well conserved diet
DISEASE: Ulcerative disease AGENT: Unknown SYNDROME Skin ulceration; sluggish behaviour; red or white necrotic skin ulcers on the mandible and maxilla and on the caudal peduncule MEASURES: Proper management system
DISEASE: White spot AGENT: Myxobacteria TYPE: Bacteria SYNDROME: Fish remain at water surface in vertical position and swim sluggishly; white spots on skin around the mouth and gills MEASURES: Antibiotics in feed (chloramphenicol, terramycin or oxytetracycline) as preventive measure; subject catfish larvae to furaltadone at 50 ppm/hour
DISEASE: Aeromonas septicaemia AGENT: Aeromonas hydrophila TYPE: Bacteria SYNDROME: Fraying and reddening of fins; de-pigmentation; ulcers MEASURES: Oxytetracycline; sulfamethoxine; ormetoprin in feeds
DISEASE: Motile Aeromonad Septicaemia AGENT: Aeromonas sp. TYPE: Bacteria SYNDROME: Exophthalmia and distended abdomen; deep dermal ulcers with haemorrhages and inflammation MEASURES: Avoid stress; use supplemental feed mixed with Trimethoprim and Bactrim for 10 days
DISEASE: Water mould AGENT: Saprolegnia spp. TYPE: Fungi SYNDROME: Grey/white patches on skin, fins, gills and eyes resembling cotton-wool; affected eggs show the same signs; normally small, focal infections spreading rapidly over body or gills MEASURES: Malachite green bath (5 mg/litre for one hour) or sodium chloride (5% for one to two minutes); avoid mechanical damage and other kinds of stress
DISEASE: Parasites AGENT: Costia sp., Chilodonella, Trichodina TYPE: Protozoans SYNDROME: Fish remain at water surface in vertical position, or nervously scratch the head and side on container bottom; skin covered with a thin whitish grey mucus; massive death can occur MEASURES: Formalin (25-50 mg/litre); Dipterex (0.25 mg/litre)
DISEASE: Parasites AGENT: Gactylogyrus sp. Gyrodactilus sp. TYPE: Trematodes SYNDROME: Same as protozoans above MEASURES: Formalin (25-50 mg/litre); Dipterex (0.25 mg/litre)
DISEASE: Parasites AGENT: Henneguya sp. TYPE: ProtozoansSYNDROME In fingerlings of C. gariepinus x Heterobranchus sp. hybrid, white spots on skin and gills observedMEASURES: Antibiotics in feed (chloramphenicol, terramycin or oxytetracycline) as preventative measure
DISEASE: Parasites AGENT: Cysticerca sp. TYPE: Nematode worms SYNDROME: Worm perforates muscled and viscera; usually found in reservoirs; fish appear not to suffer from presence of this parasite MEASURES: Unknown
DISEASE: Gill and/or external parasites AGENT: Trichodina maritinkae TYPE: Protozoans SYNDROME: Small white spots on skin or gills; irritation, instability, lethargy, weakness, loss of appetite, and decreased activity; gills pale and very swollen MEASURES: Formalin or salt solution bath
Most of the diseases listed above are principally observed within intensive culture. Prevention through avoidance of stress is probably the most effective means of avoiding diseases. So far, virus related diseases have not been reported in African catfish. Chemicals are only used when an epizootic has been detected, and then only for limited periods of time.