Influence of diet on ongrowing and nutrient utilization in the common octopus ( Octopus vulgaris)

Octopus vulgaris ongrowing has recently begun to develop in Spanish coastal waters. The need to diversify aquaculture products in terms of its biological and market potential makes octopus a serious candidate for rearing. Ongrowing success depends on several factors, such as environmental rearing conditions, diet and nutritive utilization. Two fresh diets of low market value ( Boops boops and Sardina pilchardus) were used to assess growth rate, feeding rate and efficiency by means of multiple regression analysis. Factors considered were sex and diet as qualitative variables, and body weight and temperature as quantitative ones. No significant differences were observed regarding growth and sex although it was slightly higher in males. Nevertheless, food intake was higher in females as well as in the sardine-fed females. Growth with bogue-fed octopus was significantly higher. Smaller specimens grew more than the larger ones in proportion to initial body weight. The rise in temperature increased growth and food intake over our experimental range. Differences in growth may have been due to the different lipid content of the diets since digestibility of lipid in cephalopods is poor and their main energy source is protein. The higher food intake in females may be caused by metabolic changes related to the reproduction period although this remains to be confirmed.