This giant fish is similar to the Malabar grouper, and its colour changes with age. The giant grouper has a large mouth and a rounded tail. Juveniles have irregular black and yellow markings, while adults are green-grey to grey-brown with faint mottling, with numerous small black spots on the fins.
The first fish to undergo chemotherapy was Bubba a giant grouper at the Shedd Aquarium in Chicago USA.