This dataset gathers total species richness, total abundance and total biomass of fishes recorded in six Mediterranean Marine Protected Areas in summer by underwater visual censuses performed on rocky areas at varying distances from the core of the MPA. Belt transects (25 x 5 m) were run parallel to the coast between 6 and 12 m depth, except in Tabarca Posidonia beds (50 x 5 m). Additionally, reduced fish species richness, abundance and biomass excluding zooplanktivorous fish species (Atherinidae, Clupeidae, Centracanthidae, Engraulidae, Pomacentridae, and the Sparidae Boops boops) were given as their fluctuating abundance and aggregative behavior may mask the effect of protection. Location of the 6 Mediterranean Marine Protected Areas