FISH HEALTH MANAGEMENT 277 



aquatic environments as an algicide and also has been an effective control 

 for a variety of ectoparasites, including such protozoans as Trichodina, Cos- 

 tia, Scyphidia (Ambiphrya), and Ich. Its major drawback is that its toxicity 

 to fish varies with water hardness. It is highly toxic in soft water. Copper 

 sulfate never should be used as an algicide or parasite treatment unless the 

 water hardness is known, or unless a test has been run to determine its tox- 

 icity to fish under the circumstances in which it is to be used. Even where 

 it has been used with previous success, it should be used carefully; in at 

 least one situation, dilution of a pond by heavy rainfall reduced water 

 hardness to the point that previously used concentrations of copper sulfate 

 killed many catfish. 



Copper sulfate generally is used as an indefinite pond treatment. As a 

 rule of thumb, the concentration to use varies with water hardness as fol- 

 lows: at 0-49 parts per million total hardness (TH), do not use unless a 

 bioassay is run first; at 50-99 parts per million TH, use no more than 

 0.5-0.75 part per million (1.35-2.02 pounds per acre-foot); at 100-149 

 parts per million TH, use 0.75-1.0 part per million (2.02-2.72 pounds per 

 acre- foot); at 150-200 parts per million TH, use 1.0-2.0 parts per million 

 (2.72-5.4 pounds per acre-foot). Above 200 parts per million TH, copper 

 rapidly precipitates as insoluble copper carbonate and loses its effectiveness 

 as an algicide and parasiticide. In hard-water situations, a bioassay should 

 be run to determine the effective concentration needed. It may be neces- 

 sary to add acetic acid or citric acid to hard water to keep the copper in 

 solution. The commonly used ratio is 1 part CUSO4 to 3 parts citric acid. 



Although copper sulfate has been touted as an effective control for cer- 

 tain external bacterial infections, such as bacterial gill disease, fin rot and 

 columnaris, and fungal infections, it has proven to be ineffective against 

 these diseases on warmwater fish. Other chemicals are much better for con- 

 trolling these organisms. 



Copper sulfate should be used with great caution, if at all, in warmwater 

 fish ponds during the summer, particularly if an algal bloom is present. 

 Copper sulfate is a very potent algicide, and it quickly can cause oxygen 

 depletion by killing the bloom. Therefore, it should be used in hot weather 

 only if adequate aeration devices or fresh water are available. 



POTASSIUM PERMANGANATE (KMnOj 



Potassium permanganate (registered by the Food and Drug Administration) 

 is 100% active. It is used widely in warmwater fish culture as a control for 

 external protozoan parasites, monogenetic trematodes, and external fungal 

 and bacterial infections. Because it does not deplete oxygen levels, KMn04 

 is a safe treatment in warm temperatures and in the presence of algal 

 blooms. 



