The energy requirements of Eurasian perch (Perca fluviatilis L.) in intensive culture

Fish feed constitutes one of the largest costs in aquaculture, therefore inefficient feed management will have a negative impact on fish farm economics. Eurasian perch (Perca fluviatilis L.) is a relatively new candidate for freshwater aquaculture, however little is known about the energy requirements of this species. The aim of this study was to develop an energy requirement model for intensive culture of Eurasian perch reared at rational temperatures. Data on growth (the thermal unit growth coefficient, TGC, 3√g ‧ (℃ ‧ days)-1) and digestible energy need (DEN, kJ DE ‧ g -1) of Eurasian perch at a size range of 20–180 g and at temperatures of 17–23 ℃ were used. Regression analysis revealed that both TGC and DEN were affected significantly by fish size (P <0.001) but not by temperature (P > 0.05). Two models including body size of the fish were developed: (i) an inverse TGC model for evaluation of the daily theoretical weight increment (TWi, g ‧ day)1) and (ii) a linear DEN model. The TGC model was validated by comparing theoretical data with data obtained from a commercial growth trial. By combining the TWi and the DEN, a model describing the daily theoretical energy requirement (TER, kJ ‧ day)1) at different temperatures and for Eurasian perch of different sizes was successfully developed.