The thick bodied blue gropers have peg teeth, heavy scales, a large tail and thick lips. Juveniles are brown to green brown. Adult females are brown to reddish-brown. Each scale may have a darker red spot. The adult males have the bright blue colouring that give the fish their name. The blue can range from deep navy to cobalt blue, and there may also be darker or yellow-orange spots or lines around the eyes.
All blue gropers begin their life as females. As they mature, the go through an initial phase, in which they may be male or female, before developing their adult colouring and reaching the terminal phase. Eastern blue gropers have been known to grow to 1.2 metres (4 ft) in length and weights of 22 kilograms, although fish over 15 kg are rare. The western species is larger, reaching 1.6 m and 40 kg.
The fish live in a variety of coastal waters, especially exposed reefs. The Western blue groper lives in water 5-65 m deep, and the eastern species from the shallows up to 40 m deep. They feed on invertebrates such as sea urchins, crabs and mussels. For the eastern species, spawning occurs from July until October, in estuarine seagrass beds, where the juveniles are usually found.
In 1996, the Eastern blue groper was made the state fish emblem of New South Wales.