Ecological variations of habitat diversity and reef fish communities were investigated at Marsa Gabal El-Rosas reefs, north Marsa Alam, Red Sea. Bathymetry and reef profiles were descripted over different habitats at Marsa Gabal El-Rosas reefs. A total of 148 fish species representing 34 families were counted. Transect 6 (T6) had the highest number of species (117 species), while the transect 2 (T2) had the lowest number (40 species). Pomacentridae was the most abundant group at Marsa Gabal El-Rosas reefs. The abundance and distribution patterns of six fish families (Pomacentridae, Labridae, Acanthuridae, Chaetodontidae, Serranidae and Scaridae) were descripted over different habitats at study sites in Marsa Gabal El-Rosas. Some families (Pomacentridae and Serranidae) showed increasing at outer reefs rather than inner reefs; while the others not shows obvious pattern. The dominant trophic guilds in Marsa Gabal El-Rosas reefs were Planktivores, invertebrate-fish feeders, and to a lesser extent, piscivores. Planktivores, invertebrate-fish feeder and herbivores were the most dominate trophic categories at study areas.