Juvenile pikeperch, Sander lucioperca (L.) were reared in recirculating aquaculture systems for 55 days and fed a commercial trout diet (group CD) or diets supplemented with the following vegetable oils (VO): rapeseed (group RO), soy (group SO), sunflower (group SFO). The level of feed supplementation with VO was 84% of the total crude fat (CF), which was achieved by adding 160 g VO kg-1 feed to the commercial feed base that contained 30 g CF kg-1 feed. The diets tested did not have a significant impact on the proximate composition of the whole fish, fillets, or viscera (P > 0.05). Significant differences were noted in the protein and fat contents of the pikeperch livers; these were significantly higher in the groups fed diets supplemented with VO (P < 0.05). The fatty acid (FA) profiles of the pikeperch body parts (whole fish, fillets, viscera, liver) analyzed reflected the proximate composition of the diets applied. The FA profiles of pikeperch muscles were the most stable. The diets tested did not have a significant impact in the fillets of fish from the VO groups on the value of summed products of polyunsaturated FA from the n-3 family (n-3 PUFA) to the PUFA from the n-6 family (n-6 PUFA) (n-3/n-6 ratio) (P > 0.05). They were, however, significantly lower than the values noted in group CD (P < 0.05) (1.03-2.07 vs. 3.50).
