The first part includes full fish underwater visual census data at Cape Eleuthera, the Bahamas. The data are divided into the four sites (Tunnel Rock, Cathedral, Some2C and Ike's Reef) and further into species. Per species per site and per total length (cm) class, the number indicates the total count of individuals from all eight transects combined. The second part includes carbon and nitrogen stable isotope data (δ13C-PDB and δ15NAIR) of bulk white muscle tissues (from fish individuals of varied sizes of species top species comprising 80% of the total biomass of each 5 cm total length class) collected at these four sites and adjacent water.