INVESTIGATIONS ON TECHNOLOGICAL PARAMETERS IN INTENSIVE REARING OF PIKE-PERCH (STIZOSTEDION LUCIOPERCA)

Market demands and competition force the production of high quality freshwater fish in European aquaculture. In Hungary pike-perch is the most „noble” and perhaps the most sensitive fish species. One of the constraints of the increasing its production in natural waters, reservoirs and ponds is the shortage in adequate sized alevins. The possible solution of this problem can be the elaboration of intensive rearing technics of pond prereared fry. The aims of the present work were to test the growing capacity, feed conversion and survival of pike-perch in intensive circumstances. Fish were kept in 130 l aquaria working in recirculation system at an average water temperature of 220.5 C. Two stocking densities were applied (18 and 36 fish/aquarium). Minced fish (test) and live prey (control) were offered twice a day till satiation in two replications. The experiment lasted 4 weeks. According to our results minced fish is suitable feed in the intensive rearing of pike-perch alevins. Daily food intake was only influenced significantly by different feeds (2.01g vs.4.53 g, test and control, respectively). Feeding and stocking density had significant effect (P=0.001 and 0.017) on the average weight gain (0.52 g and 1.40 g for minced fish and live feed, respectively, 1.02 g in lower and 0.90 g in higher density). Owning to the high variances treatment effect on feed conversion proved to be not significant. Average survival of the minced fish fed group was 62.2 % vs. 78.8 % of the live fish fed alevins. This difference was significant (P<0.01) in the first two weeks when almost all of the losses happened due to cannibalism and other unknown reasons. Based on our results a period of 10–14 days is needed for pre-reared pike-perch to change gradually their feeding from zooplankton to minced fish diet.