Growth, protein retention and biochemical composition in Octopus vulgaris fed on different diets based on crustaceans and aquaculture by-products

The octopus, Octopus vulgaris, is one of the main targets for aquaculture diversification in Mediterranean countries. However, the development of octopus farming is limited by the lack of information regarding nutritional requirements of this species during its life cycle. In this study, five diets were tested on the biological performance (growth, protein retention and biochemical composition) of individually reared octopuses (n=8 per diet), including three single diets constituted by: an endemic crab (the white crab, Plagusia depressa), a commercial crab imported frozen (the blue crab, Portunus pelagicus), and bogue (Boops boops) discarded from fish farms (aquaculture by-product), as well as two mixed diets, containing a 60-40% of blue crab-bogue and white crab-bogue, respectively. The rearing period lasted 8 weeks. Octopuses that fed on a mixed diet constituted by blue crab-bogue showed a higher growth than those feeding on bogue as a single food item. No significant differences in growth were observed among individuals feeding on single food items. Highest protein retention was observed in octopuses fed on diets containing discarded bogue, associated with a high lipid and monoenes content in this food item, underlying the use of lipid as energy source in O. vulgaris. However, discarded bogue was deficient in ARA in comparison with octopus tissues, which did not seem to affect growth during the experimental period. These findings underline the potential of aquaculture by-products, particularly bogue, as an adequate diet for culturing O. vulgaris. (C) 2011 Elsevier B. V. All rights reserved.