Effect of different proportions of crab and squid in semi-moist diets for Octopus maya juveniles

During the present study, the effect of five semi-humid experimental diets with different proportions of crab and squid were tested, on juveniles of the red octopus, Octopus maya. For this, five prepared diets based on crab and squid (SC50, SC60, SC70, SC80, and SC90; the number indicates the percentage of squid in each diet), were fed to juvenile O. maya during 60 days. Feeding and growth rates, survival, glycogen content in muscle, soluble protein and digestive enzymes activity in digestive gland (DG), fatty acids and amino acid composition of diets and octopus juvenile were determined. Higher growth, survival and nutritional condition was obtained with diets SC50, SC60 and SC70 compared to SC80 and SC90 (P< 0.05). A direct relation between glycogen concentration in the muscle and the digestive gland (DG), as well as soluble protein in the DG were also obtained for octopuses fed these three diets. Higher alkaline and acid protease activity were found on octopuses fed SC60 and SC90, respectively (P< 0.05). Results suggest that a proportion of 70% squid and 30% crab may be considered adequate to satisfy nutritional requirements for the fattening of O. maya juveniles. Nevertheless, a proportion of 30% of crab in the diet, is still high, regarding production costs and profitability, and further research will focus on the total replacement of crab by less expensive raw material with similar nutritional value, to increase economic viability of commercial O. maya culture.