WEANING OF DOVER SOLE ( Solea vulgaris ) USING ARTIFICIAL DIETS

We conducted three experiments in which several types of weaning diets were compared using one‐month‐old soles which had been fed previously on living Artemia. The diets were: a) ground and frozen molluscs ( Laevicardium crassum ), b) dry pelleted diet stabilized with corn gluten (14%) including different attractive matter (ground polychaetes [Nephthys hombergii] or molluscs, 10% of the diet dry basis), c) the same dry pelleted diet lacking attractive matter, d) wet paste containing 50% of ground molluscs dry basis, and e) dry pelleted diet stabilized with 15% sodium algin. Fish were examined after 55 days of feeding on the diets. In spite of large variability of growth, several facts were apparent. The presence of attractive matter seemed to enhance food intake and, consequently, growth. Concerning ground polychaetes, the attractant was found in the liquid phase after high speed centrifugation. Contrary to previous observations, frozen molluscs and wet paste containing ground molluscs did not give good results, especially for growth. The best results were obtained with dry artificial diet stabilized with algin. This seemed to be due to the high stability in water of the diet. Weaning is an important step in the life of fishes and only a few of them can go through it with few difficulties. However, the growth of these latter fishes is similar to that of fish fed living prey.