DISEASE CONTROL 



water. This stock solution is mixed 

 thoroughly and quickly with the 

 water in the pond. To ensure an 

 even distribution of the disinfectant 

 and to aerate the water dtiring 

 treatment, the w\ater should be re- 

 circulated in a closed system from 

 the lower end of the pond to the 

 upper end b}' means of a centri- 

 fugal pump. 



Prolonged treatments can be car- 

 ried out easier if fish are not fed 

 for 24 hours before treatment. This 

 reduces the fishes' metabolism rate 

 and oxygen requirement. Accord- 

 ing to Fish (1947), for safe treat- 

 ment, fish should not be too 

 crowded; there should be no more 

 than that 1 part of fish by weight 

 to 100 parts of water ( 1 pound of 

 fish per 12 gallons of water). If 

 such a ratio is maintained, the flow 

 of water or aeration can be cut off 

 for 1 hour. 



Gammexajie has been described as 

 an effective treatment for infesta- 

 tion with ArguJus, a copepod. It 

 should be added at a rate of 1 part 

 to 10 million parts of water to the 

 pond or tank holding the infested 

 fish. In tanks, the medicated water 

 should be replaced with fresh water 

 after 2 to 3 days of treatment. 

 How effective ganxmexane is for the 

 treatment of infestations caused by 

 Lernea (another copepod) is not 

 known at this time. 



The most-frequently used pro- 

 longed treatments are with formalin 

 and pyridylmercuric acetate, tech- 

 nical (P.M.A.). Formalin is added 

 to water at a rate of 1 part of 

 formalin (containing about 40 per- 



cent formaldehyde) to 4,000 parts 

 of water by volume. Pyridylmer- 

 curic acetate (P.M. A.) is used at a 

 rate of 2 parts per million. Treat- 

 ment with formalin is effective 

 against many of the external para- 

 sites, like Gyrodactyhis^ DaHyJogy- 

 rus^ Chilodon., Costia^ Trichodina^ 

 fin rot, and others. A 10-percent 

 stock solution of P.M.A. can be 

 easily prepared and kept on hand 

 when needed. P.M.A. is used 

 mainly for the treatment of gill 

 diseases, but some of the external 

 parasites listed here are also af- 

 fected by it. P.M.A. is toxic to 

 some fish, like rainbow trout. It 

 is not known how toxic it may be 

 to minnows and other bait fishes. 



Antibiotics, such as chloram- 

 phenicol and terramycin, have been 

 found to be effective in the control 

 of ulcer disease and furunculosis in 

 trout and red-leg disease in frogs. 

 Since the bacterium PseudoDionas 

 {Aeromonas) hydrophila^ which 

 causes red-leg disease is identical 

 with that which causes infections in 

 many warm-water fishes, chloram- 

 phenicol may be the choice in treat- 

 ment of infections of aquarium 

 fishes. It sjiould be added to water 

 in which fish are kept at the rate of 

 50 milligrams per liter (190 milli- 

 grams per gallon of water ) . Water 

 should be changed once a week and 

 fresh chloramphenicol added. 

 Chloramphenicol is also available 

 in capsules, each containing 250 

 milligrams of the drug (1 capsule 

 per 5 liters or 1.3 gallons of water). 

 If fish are kept in flowing water, 

 flow should be stopped for 1 hour 



55 



