Pair and harem formation, nest-building and courtship behaviour of the marine ornamental fish

The Brazilian basslet (Gramma brasiliensis) is an ornamental fish species of significance to the fish market, and the development of a breeding protocol is of interest to the aquarium trade. There is little information regarding the behaviour of G. brasiliensis in captivity; thus, the aims of this study were to: (1) investigate pair and harem formation in different-sized aquaria (70 and 110 L) and tanks (150 and 310 L); (2) investigate the choice of different macroalgae species and synthetic materials by the fish for nest building in captivity; and (3) describe the courtship behaviour of captive fish and compare it with available literature for G. brasiliensis and Gramma loreto in natural environments. Based on the results, we suggest that G. brasiliensis should be kept in pairs because of their aggressive behaviour. Macroalgae of the genus Chaetomorpha and all synthetic materials were used by the fish to build nests. The courtship behaviour of G. brasiliensis in captivity is described for the first time and is similar to that reported for G. loreto in a natural habitat, namely ‘U-turn with body quivering’.