Groupers are teleosts, typically having a stout body and a large mouth. They are not built for long-distance, fast swimming. They can be quite large, and lengths over a meter and the largest is the Atlantic goliath grouper (Epinephelus itajara) which has been weighed at 399 kilograms (880 pounds) and a length of 2.43 m (7 ft 11+1⁄2 in), though in such a large group, species vary considerably.
Their mouths and gills form a powerful vacuum which pulls their prey in from a distance. They also use their mouths to dig into sand to form their shelters under big rocks, jetting it out through their gills