Effects of fish hydrolysate (CPSP®) on growth and digestive gland lipid composition of Octopus vulgaris (Cuvier, 1797) juveniles

Effects of artificial diets were tested on growth and digestive gland (DG) lipid composition of juvenile Octopus vulgaris. For Experiment I, three diets were used: (i) SQUID (Loligo gahi) as a control diet; (ii) Squid paste and fish hydrolysate CPSP®, agglutinated with gelatine (GEL20); and (iii) Squid paste, fish hydrolysate CPSP® and gelatine (GEL40). For Experiment II, three diets were used: (i) SQUID, control diet; (ii) Squid paste, CPSP® and alginate (ALG10); and (iii) Squid paste, CPSP® and alginate (ALG20). For both experiments, growth rates for octopuses fed control were higher (P < 0.05), while artificial diets were not different (P > 0.05) between them. All diets promoted similar growth, regardless of the different CPSP® concentrations and binders. Growth rates obtained were among the highest obtained for O. vulgaris with artificial diets until now. The lower growth obtained with the artificial diets was greatly reflected in the DG fatty acid composition. The most important fatty acid groups, such as n-3 highly unsaturated fatty acids, decreased in the DG of animals fed artificial diets. Lipid content, particularly neutral lipids, was higher in the DG of octopuses fed squid, indicating higher nutritional condition of these animals compared to those fed the artificial diets.