Fish Hatchery Management - fisheries & aquaculture

FISH HEALTH MANAGEMEN'I' 335Masoten at 0.25 part Per million active as a pond treatment, repeatedfour times at weekly intervals, gives good control of anchor worms. However,inconsistent results are obtained when water temperatures exceed80"F or when the pH is 9 or higher. During summer months, Masotentreatment should be applied early in the morning and it may be necessaryto increase the concentration to 0.5 part per million active for best results.Packing and Shipping SpecimensSeveral state agencies have laboratories with biologists trained in the diagnosisof fish diseases. In addition, several fish-disease laboratories and anumber of trained hatchery biologists in the United States Fish andwildlife Service are available for help in disease diagnosis. In recent yearsprivate consulting biologists also have set up practices in disease diagnosis.Correct diagnosis depends upon accurate and detailed information regardingthe fish and the conditions under which they were raised, andespecially upon the proper preparation of material that will be shipped to afish-disease laboratory. The more informationlikely that the diagnosis will be correct.If, after a preliminarythat is available, the morediagnosis in the hatchery, some treatment alreadyhas been started, specimens and information nevertheless should be sent toa disease laboratory for verification. Although the symptoms may seem typical,another disease may be present. It is not uncommon to have twodisease conditions present at the same time, one masking the other.Although treatments may be effective for one condition, the other diseasemay still be uncontrolled. Hatchery personnel should furnish the laboratorywith correctly collected and handled material, including all available information,at the earliest possible date. If the required information is not furnishedwith specimens, conclusiae diagnosis ma! not be possible.To facilitate the packing and shipping of proper specimens and information,a comprehensive checklist, such as the Diagnostic Summary Informationform (Figure 106), should be included. All instructions and questionsshould be read carefully. All questions should be answered. If an answercannot be furnished, or a question is not applicable, this should be indicatedin each case. When disease breaks out, specimens should be collectedand preserved before any treatment is given or started. Only a few fishshould be sent for examination, but these should be collected with the utmostcare. Dead fish or fish that appear to be normal are nearly worthless.The most desirable fish are those that show most typically the sings of thedisease in question. Moribund, but still liuing fish are the best for diagnosticpurposes.