The DEMERSTOCK project aims to provide biological data on seven species of demersal fish caught on the reefs of Mayotte, so that models can be used to assess stock status. The acquisition of data such as the size, weight, maturity stage and age of the individuals caught is essential for assessing the state of commercial fish populations and stocks. To carry out this study, the following species were selected on the basis of their importance in local fisheries: bluefin trevally (Caranx melampygus), green jobfish (Aprion virescens), rusty jobfish (Aphareus rutilans), redmouth groupper (Aethaloperca rogaa), yellow-edged lyretail (Variola louti) and two deep-water red snapper (Etelis boweni and Etelis carbunculus). The project is based on collaboration with local fishermen and fishmongers to sample the defined species.