1 ISSN 1330-7142 UDK = 639.31:639.216.4 INVESTIGATIONS ON TECHNOLOGICAL PARAMETERS IN INTENSIVE REARING OF PIKE-PERCH (STIZOSTEDION LUCIOPERCA) T. Molnár (1) , Cs. Hancz (2) , M. Molnár (3) , Gabriella Stettner (4) Original scientific paper ABSTRACT 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 pre-reared 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. Keywords: pike-perch, feeding, stocking density, intensive rearing INTRODUCTION The pike-perch is one of the most noble and perhaps the most sensitive fish in Hungary. Market demands and competition force the production of high quality freshwater fish in European aquaculture. One of the constraints of the increasing pike-perch 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 pre- reared fry. It seems to be justified since the intensive rearing of its North American relative (Stizostedion vitreum) is more or less resolved. There are recommendations for the adequate stocking density (Kuipers and Summerfelt, 1994; Chesire and Steele, 1972) and encouraging preliminary results are published for the transformation to dry and semi-moist foods (Colesante et al., 1986; Kuipers and Summerfelt, 1994). Intensive rearing of the pike perch larvae on artificial diet is not viable because the previous experiments showed poor growth and high mortality (Klein Bretteler, 1989; Schlumberger and Proteau, 1991) and the pre-rearing in ponds is easy to resolve. The great growing capacity of the pre-reared pike perch can be well exploited with high value artificial foods and from 2 grams to more than 300 grams growth can be achieved on 22-26 o Our final aim was to study growing capacity, food conversation and survival of the pike-perch under intensive conditions. C temperature in a year (Hilge, 1990). _______________ (1) Tamás Molnár, Ph.D student, (2) Csaba Hancz, DSc, (3) Marcell Molnár, Ph.D student, (4) Gabriella Stettner, Researcher - University of Kaposvár, Faculty of Animal Science, Guba S. u. 40, 7400 Kaposvár, Hungary