Slaughter yield and growth performance indexes of pikeperch (Sander lucioperca (L.)) selects reared in recirculating aquaculture systems at suboptimal temperatures

The aim of the study was to determine the impact diet has on the basic growth performance indexes and slaughter yield of pikeperch selects (body weight > 1.35 kg). Tagging the individual fish with PIT tags also permitted determining the impact of sex on the studied growth performance indexes. The fish were fed two diets with protein/fat/carbohydrate ratios of 50.5/11.8/29.4 in group I and 47.1/14.1/29.0 in group II. Neither the diets nor the sex of the fish has a significant impact on the final body weight or condition of the pikeperch (P > 0.05). Significant differences were noted between the relative indicators of pikeperch growth performance (SGR and DGR) (impact of diet and sex; P < 0.05). Among the growth performance indexes analyzed, e.g., viscerosomatic (VSI), hepatosomatic (HSI), and gonadosomatic (GSI), statistically significant differences were noted with regard to HSI (impact of diet and sex) and GSI (impact of sex) (P < 0.05). The analysis of the relative values of the pikeperch body parts studied (expressed in % body weight) indicated that the studied parameters had significant impacts on the slaughter yield of the viscera (impact of sex) and skin (impact of diet), as well as on gutted whole fish, gutted and headed whole fish, fillets with skin, and skinned fillets (impact of sex) (P < 0.05). The slaughter yields of the skinned fillets of males from both dietary treatments were approximately 5% higher than those of the females.