AbstractJuvenile Atlantic cod Gadus morhua (initial mean weight = 15.6 g) were fed three isonitrogenous, isocaloric diets (55% protein, 16% fat; calculated gross energy ≈ 20.5 MJ/kg) containing dried laver (nori) Porphyra spp. (red algae) to replace 0, 15, and 30% of the fish meal in a commercially available marine finfish diet. After 84 d, no differences in survival, growth, or hepatosomatic index were found among the treatment groups. The fish attained an average weight of 41.0 g, a specific growth rate (SGR) of 1.19%, and a feed conversion ratio (FCR) of 1.26. The fatty acid composition of the muscle was similar among treatment groups except that arachidonic acid levels were greater in fish given diets with 30% Porphyra replacement. These results indicate that Porphyra spp. at levels up to 30% provide a suitable fish meal replacement in diets for juvenile Atlantic cod.
