Weaning trials with cod fry on artificial diets

Three experiments with different size groups of cod fry, 13, 49 and 465 mg wet-weight were offered 6 different artificial diets. The experiments lasted for 28 days. Growth, and for the medium size-group chemical composition and gross energy-content of the fish were measured. Mortality was recorded daily, and the fish were counted after 14 days and at end of the experiments to correct for cannibalism. Growth were similar on all diets, probably because of prominent cannibalism. Significant differences in biomass and survival were found. Survival ranged from 0 to 39 % for the smallest group and from 72 to 90 % for the largest group. Moist feed gave the best survival. About 50 % of the mortality was due to cannibalism.