The gobis and blenis (Gobiidae and Bleniidae) are the most important group of small benthic littoral fishes in tropical reefs, representing most of the high number of small fish species found in Western Atlantic. The natural history of gobiid and bleniid fish from Fernando de Noronha was assessed by means observation sessions using both snorkelling and scuba diving. Most of these observations were aimed at social behaviour, such as intra and interespecific interactions, territorial and reproductive behaviour. In general, these fish from Fernando de Noronha occurs in intertidal zone, are gregarious, with small home ranges of near 2 x 2 m², and show low agressivity towards other fish. Occasionally, some chasing was recorded between individuals of the same or distinct species. Low agressivity is probably associated to the occupation of small areas (e.g. tide pools), as a high degree of agressivity may represent an unnecessary [excessive] waste of energy. Most of the studied species presents cryptic coloration, associated to the avoidance of predators, but some males showed conspicuous coloration and intense aggressive behaviour, mainly during the reproductive season. It was only during this occasion that territorial behaviour, chasing and bites were recorded.
Preferencial habitat; reproductive aspects; social behaviour
