Four species of sympatric damselfishes (Eupomacentrus, Pomacentridae) from certain Florida reefs can be distinguished by certain sound characteristics used during courtship. Apparently the fish use these characteristics for species recognition. These characteristics involve the temporal structure of a sound, i.e. the length of the pulse interval, containing the necessary code for communication. In Curaçao members of the same species did not use the same sound characteristics for species recognition as in Florida. Strangely enough, some were able to differentiate between local congeners, but unable to recognize members of their own species. The question arises whether local dialects are in different codes, in different parts of the species’ distribution range. These populations could live in local restricted areas, as recordings from one species suggest. It is possible that apart from the temporal structure, the frequency spectrum carries important information for the identification of the species in question. This contradicts earlier conclusions.