Effects of environmental enrichment on the behavior of Octopus vulgaris in a recirculating aquaculture system

Octopus vulgaris is a commercially valuable species. It is overexploited in the natural envi-24 ronment and is considered to be an innovative species for aquaculture. However, large-scale farm-25 ing is generally designed only based on economic requirements, disregarding any form of enrich-26 ment that to induce the natural behavior of aquatic species. Although many studies have shown the 27 influence of environmental enrichment on terrestrial vertebrates, fish, and cephalopod mollusks, 28 information on the effect of environmental enrichment on the body patterns of O. vulgaris is limited. 29 Therefore, in this study, we assessed how different environmental conditions (Basic vs. Enriched) 30 affect sub-adults of O. vulgaris kept in recirculation systems, through qualitative–quantitative stud-31 ies of the main body patterns and their potential application in the commercial production of this 32 species. The results indicated that octopuses kept in the enriched environment showed several body 33 patterns and gained a significantly higher weight than those kept in the basic environment. The 34 body patterns displayed by the individuals kept in the basic environment were similar to those 35 exhibited under situations of hostility and inter/intra-specific conflict. Hence, the environment of 36 octopuses needs to be enriched, especially for the large-scale production of this species.