FISH HEALTH MANAGEMENT 281 



For the treatment of Aeromonas, Pseudomonas, and Flexibacter sp. infec- 

 tions in catfish, the nitrofurans are fed at the rate of 4-5 grams active in- 

 gredient per 100 pounds of fish per day for 7-10 days. If the fish under 

 treatment are being fed at 3% of their body weight daily, it is necessary to 

 incorporate 133-167 grams active ingredient per 100 pounds of food. Fish 

 never should be fed either of the nitrofurans for less than 7 days. 



Nitrofurans have been used as a prolonged- bath treatment for external 

 bacterial infections and as a prophalaxis during the transport of warmwater 

 fish. The levels recommended vary from 5 to 30 parts per million active in- 

 gredient. However, severe losses of channel catfish sac fry and swim- up fry 

 have occurred during treatment with 15 and 25 parts per million active ni- 

 trofurozone. Five parts per million should be adequate. It is suggested that 

 nitrofurazone not be used to treat channel catfish sac fry or swim- up fry. If 

 it must be used, apply only the lowest concentration, with caution. 



Furanace (P-7138, nitrofurpirinol) is a relatively new nitrofuran that has 

 been used to control bacterial infections of trout and salmon. It also ap- 

 pears effective against bacterial infections in catfish, although it has been 

 used only on a limited basis for that species. 



Continued treatment of catfish is discouraged because furanace may cause 

 injury to the skin during prolonged exposures. In trout and salmon culture, 

 furanace is used as a bath at 1 part per million active ingredient (0.038 gram 

 per 10 gallons; 0.283 gram per 10 cubic feet) for 5-10 minutes, or at 0.1 part 

 per million active ingredient (0.0038 gram active per 10 gallons; 0.0283 

 gram active per 10 cubic feet) for an indefinite period. It is also fed at 

 100-200 milligrams of active ingredient per 100 pounds of fish for 3-5 days. 

 Thus, if fish are being fed 3"(i of their body weight daily, it is necessary to 

 have 3.3-6.7 grams of active ingredient per 100 pounds of food. 



SULFONAMIDES 



Sulfonamides have been used since 1946 to treat bacterial infections of sal- 

 monids, but have been applied rarely to warmwater fish. They are reg- 

 istered by the Food and Drug Administration. 



Presently, sulfamerazine and sulfamethazine are the sulfonamides most 

 widely used. Generally, they are fed at a therapeutic level of 5-10 grams of 

 drug per 100 pounds of fish per day for 10-21 days. Sulfonamides may be 

 toxic to some fish species when the high dosages (lO grams per 100 pounds 

 of fish per day or more) are fed. However, with the possible exception of 

 bacterial hemorrhagic septicemia caused by Aeromonas hydrophilia or Pseu- 

 domonas fluorescens, high drug levels seldom are required. 



ACRIFLAVINE 



Acriflavine is not registered by the Food and Drug Administration. A bac- 

 teriostat, it has been used widely for many years in the treatment of 



