Background: Although fishers' knowledge has been recently considered into management programmes, there is still the need to establish a better understanding of fishers' perceptions and cognition. Fishers can provide novel information on the biology and ecology of species, which can potentially be used in the management of fisheries. The knowledge fishers have and how they classify nature is empirically based. It is common, for example, to observe that fishers' taxonomy is often represented by the generic level, one of the hierarchical categories of folk classification that is somewhat analogous to the Linnean genus, as it groups organisms of a higher rank than the folk species.In this study we compiled the knowledge fishers have on local fish, such as their folk names, diet and habitat. Methods: Five coastal communities widely distributed along the Brazilian coast were studied: two from the northeast (Porto Sauípe and Itacimirim, in Bahia State, n of interviewees = 34), two from the southeast (Itaipu at Niterói and Copacabana at Rio de Janeiro, Rio de Janeiro State, n = 35) and one from the south coast (Pântano do Sul, in Santa Catarina State, n = 23). Fish pictures were randomly ordered and the same order was presented to all interviewees (n = 92), when they were then asked about the species name and classification and its habitat and diet preferences. Results: Fishers make clusters of fish species, usually hierarchically; fishers of the coast of Brazil use mostly primary lexemes (generic names) to name fish; and fishers did not differentiate between scientific species, since the same folk generic name included two different scientific species. Fishers provide information on species to which there is scarce or no information on diet and habitat, such as Rhinobatos percellens (chola guitarfish, arraia viola or cação viola), Sphoeroides dorsalis (marbled puffer, baiacu), Mycteroperca acutirostris (comb grouper, badejo) and Dasyatis guttata (longnose stingray, arraia, arraia manteiga). Conclusions: fishers' knowledge on fish diet and fish habitat can be strategic to management, since their knowledge concentrates on the fishery target species, which are the ones under higher fishing pressure. Besides, fishers showed to have knowledge on species still poorly known to science. [ABSTRACT FROM AUTHOR]