Parasitoses in the Fry of Selected Freshwater Fish Species Under the Conditions of Stripping and Rearing

Abstract

During the period from 1984 to 1989 the problem of parasitic invasioninto the artificially reproduced and reared fry of the freshwater fishspecies (Barbus barbus, Chondrostoma nasus, Leuciscus cephalus, Aspiusaspius) were investigated at a specialized fish breeding farm of theCzech Angler's Union in Trebic-Pousov situated on the river Jihlava (theDanube river basin). The invasion with parasites was investigated in 979fish specimens (846 juvenile, 133 adult) of the selected species and in257 fish of other species.The reared fry of the selected fish species were found to be endangeredalready in their first days of life, predominantly by ectoparasiticprotozoa with not definitely formed host specificity.Thus optimal rearing conditions have to be assured, along with regularexamination of the health status. Efficient preventive antiparasiticbaths have to be applied. It is advantagenous to complement thesemeasures with an effective way of sanitation of the fish-rearing farms,by the investigation of the health status of fish in the feeder of thefish-hatchery and rearing pond with its regulated stocking, or possiblyby declaring relevant areas as being protected with the introduction ofa closed turnover of the parent fish shoal.