Fish Hatchery Management - fisheries & aquaculture

278 FISH HATCHERY MANAGEMENTRecommendations lbr its use vary from 2 parts per million (5'4 poundsp", u.."-foot) to as much as 8 parts per million (21.6 pounds per acre-foot)as an indefinite pond treatment. At 2 parts per million it is not toxic tocatfish or centrarchids, but it can be very toxic at greater concentrationsunless there is a significant amount of organic matter in the water. Therefore,before a concentration higher than 2 parts Per million is used, it isimperative that a bioassay be run with both fish and water from the unit tobe treated. In most situations, it is best to use 2 parts per million eventhough the treatment may have to be reapplied within 24 hours to be effective.It has been recommended that 3 parts per million be used to treat troutwith excessive gill proliferation associated with chronically poor environmentalconditions. However, as in all cases, it is best to test this concentrationon a few of the trout before it is applied to the entire lot'Potassium permanganate imparts a deep wine-red color to water. Uponbreaking down, the color changes to dirty brown. If a color change occursin less than 12 hours after KMnOa has been applied, it may be necessaryto repeat the treatment.Potassium permanganate also is used widely to help alleviate oxygen deficienciesin warmwater ponds. Although it does not add oxygen to thewater, as has been suggested by some, it does help reduce biological oxygendemand by oxidizing organic matter in the pond'qUATERNARY AMMONIUM COMPOUNDSQuaternaryammonium compounds are not registered by the Food andD-rug Administration. Such chemicals as Roccal, Hyamine 3500, and Hyamine1622 are bactericidal but will not kill ectoParasites. They generallyare used for controllingexternal bacterial pathogens and for disinfectinghatcheryequipment.Likemanychemicalsusedinexternaltreatments'they become more toxic at high temperatures and in soft water. Thequaternary ammonium compounds commonly are used to treat salmonidsfor bacterial gill disease. A standing bath of 2 parts per million (active ingredients)of Hyamine 3500 or Roccal for one hour usually is successful'i{yr,'u.r" 1622 has been used by some culturists who find Hyamine 3500too toxic for salmon fingerlings. Treatments should be conducted for 3 or 4consecutive daYs.Quaternary ammonium compounds may be purchased as liquids of variousstrengthr. e SO.f solution is an excellent consistency to use but, whenexposed to air, it may evaPorate, changing the concentration' Hyamine1622 may be purchased as a 100% active-ingredient powder that goes intosolution easily when added to warm water but tends to form a sticky massifwaterispouredoverit'Arespiratorshouldbewornwhenthiscompoundis used.