Feed Intake, Feed Efficiency, Growth, Body Composition, and Blood Chemistry in Reciprocal Crosses of Wild and Farmed Olive Flounder, Paralichthys olivaceus

Triplicate groups of wild and farmed purebred offspring and their reciprocal hybrids in olive flounder, Paralichthys olivaceus (body weight: 3.8–4.9 g), were fed to apparent satiation for 112 d. Body weight, feed intake, and feed efficiency were analyzed as repeated measures, with initial weight as a covariate. The effect of cross type on body weight and feed intake was highly significant ( P < 0.0001). Final body weight was highest in the farmed purebreds and lowest in the wild purebreds among the four crosses. The farmed purebreds had the highest feed intake during the initial 28 d. Feed efficiency was independent of cross type ( P > 0.1). At the end of the feeding trial, the n‐3 highly unsaturated fatty acid content was highest in the hybrid cross type from farmed females and wild males, and consequently, crossbreeding could be advantage for the trait. The serum alanine aminotransferase activity was highest in the wild purebreds among crosses. This result may be involved in growth inferiority of wild purebreds, following the deficiencies in artificial diet adaptability. We suggest that the growth differences between the purebred wild and farmed olive flounder result from the differences in relative feed intake, and appear to be based on additive genetic variation due to mid‐parent values of hybrid.