Along with the blacktip reef shark ("C. melanopterus") and the whitetip reef shark ("Triaenodon obesus"), the grey reef shark is one of the three most common sharks inhabiting Indo-Pacific reefs. They actively expel most other shark species from favored habitats, even species larger in size. In areas where this species co-exists with the blacktip reef shark, the latter species occupies the shallow flats, while the former stays in deeper water. Areas with a high abundance of grey reef sharks tend to contain few sandbar sharks ("C. plumbeus"), and "vice versa"; this may be due to their similar diets causing competitive exclusion.