Recently most research on cephalopod culture has focused on the development of new specific enrichments for paralarvae and compound feeds for juveniles and sub-adults. However, little research has been conducted in order to test new rearing systems, specifically designed to meet the particularities of these species. This experiment was set to compare the biological performance of Octopus vulgaris reared under traditional group conditions in floating cages (5 m3) and individually in net cages (80 L), in two successive ongrowing trials. Octopuses (1565 ± 263 g) were fed a mixed diet containing crab and fish during 60 d.
In general, higher mortality was observed in octopus reared under group conditions (28.1–36.7%) rather than individually (0–12.5%), related to breeding behavior and to weight dispersion along both trials. This led to highest biomass increment in octopus reared individually. However, the group rearing system had a positive effect on growth, reflecting in higher biomass increment and food conversion rates until 40–50 d of rearing. Accordingly, in order to maximize profitability of traditional group on growing, periodic grading and selection of males during the reproductive period are recommended. In addition, no difference in proximate composition and fatty acid profile was found in muscle regardless of rearing system.