Growth and survival of Octopus vulgaris (Cuvier 1797) paralarvae fed on three Artemia-based diets complemented with frozen fish flakes, crushed zooplankton and marine microalgae

During one month, paralarvae of common octopus (Octopus vulgaris) were fed 3 different diets: (I) Anemia sp. enriched with Isochrysis galbana (AI) complemented with sand eel (Hyperoplus lanceolutus) flakes (AH); (2) Artemia sp. enriched with crushed marine zooplankton (AZ); and (3) Anemia sp. cultured with Isochtysis galbana and further enriched with the microalga Nannochloropsis sp. (AN). The highest dry weight (1.6179 +/- 0.3861 mg) was registered with the AN diet and the best average survival (67.0%) with the AZ diet. Considering the highest dry weight obtained, the moderate high survival and the fact that with this diet it was possible to attain the adult stage, the AN diet was the most appropriate. The reasons for the best result in growth observed with AN are discussed as: (I) the combination of docosahexaenoic acid (DHA) provided by Isochrysis galbana and the high eicosapentaenoic acid (EPA) content present in Nannochloropsis sp.; (2) the fact that the higher protein/lipid ratio of this diet improves the final dry weight of the paralarvae; and (3) the fact that Nannochloropsis sp. could inhibit the harmful microflora growth in the rearing tank. Regarding nutritional aspects, DHA content per se is not the only determinant factor for growth and survival of O. vulgaris paralarvae, but the presence of a high protein/lipid ratio and a high phospholipid content in the diet could possibly explain the better quality and strength of the paralarvae.