Study on the effect of two different methods of diet change on the growth of pond reared pike-perch (Stizostedion lucioperca L.)

Abstract

One of the constraints of the increasing the production of pike-perch in natural waters, reservoirs and ponds is the shortage in adequate sized cdevins. The living conditions of the most sensible age-groups (embrió, larvae and fry) should be altered by different techniques during the pike-perch rearing. It is provided in pond pre-rearing in the first 4-6 week of life, but in case of fingerlings the possible solution of this problem can be the elaboration of intensive rearing technics of pond pre-reared fry. The aims of our work in 1999-2001 were to examine the possibility of converting pond reared, zooplankton feeding pike-perch fry to feed on not living food. During the 4 weeks of experiments, the effect of changing the diet from zooplankton to minced fish with and without acclimatisation was studied in aquaria, working in an intensive, recirculating system. According to our results the converting offeeding of pond reared pike-perch fry to minced fish is feasible with both of the conversion technics, but there were differences between the production parameters. The food intake (with acclimatisation: 11.67±1.04, without acclimatisation: 7.75±4.26 g/fish) and feed conversion (2.84 and 5.2 g/g) were influenced significantly (P=0.05) by the diet changing method. The effect on the average weight gain (4.38±0.68 and 1.54±1.02 g/fish) was also found significant (P=0,01). In case of mortality (16.3 and 22.2%) the difference was not significant. Cannibalism was only detected in case of conversion without acclimatisation in the first two weeks (1.85 and 5.55%).