Gill Disease

There are a few disease of the gills of fishes which can all be clumped into one group. "Bacterial gill disease," caused by myxobateria, is common in every hatchery and wholesale supply house and, unfortunately, there is little done to assist the fish.

Symptomatically the fish infected first become sluggish and refuse to eas. Then the gills become slimy. This sliminess is hard to see under ordinary circumstances, but soon the slime becomes so thick that bits of debris from the water become adhered to the film and it can be seen to stick out from the gills as a sort of streamer of slime. If a fish is closely examined its gill filaments will be noted to have a swollen and congested appearance until finally they get a deep red. Past this stage the gill filaments become thickened at their extremities and get very pale. Once the disease has advanced this far the gills usually become fungused. The fungus infection will ordinarily attack the gills first and then spread over the head. It is difficult to save the fish once it reaches this stage.

Treatment is simple if the disease is discovered in its initial stages. Terramycin or Tetracyn, 500 mg. per 5 gallons of water each day for 5 days will easily control the bacteria. Keep the infected fish under antibiotic treatment for two weeks. Some workers have advised the use of copper sulfate solution (1:2,000) in which the fish are bathed for 30 seconds. Twice a day for two days. This is not to be recommended for smaller fishes as the copper sulfate is poisonous to them. PMA (pyridylmercuric acetate technical) can be used and a 30 minute bath in a 1:400,000 solution is sufficient.