Groupers along with sea basses and hamlets, are in the seabass family, which is called Serranidae. There are more than 85 species found worldwide. Groupers are relatively long-lived (up to 40 years) and reproduce for only a short period of time, making them especially vulnerable to overfishing.
Groupers are generally quite large fish when mature, but many of the juvenile forms are favorite aquarium specimens. Most groupers are hardy though there are a few that are more difficult to keep. All Grouper species are a predatory fish. They inhabit temperate and, especially, tropical waters. Groupers vary in size from the large Australian grouper, which measures 3.5 m, to species measuring less than 10 cm. Most groupers can change their coloration. Some, such as the blue-spotted argus, can do this almost instantaneously, changing from a dark to a light color when feeding or alarmed. The blackfin grouper is dark red when taken in deep waters but much lighter when taken in shallow waters. The smaller species that show spectacular color changes are highly valued by aquarists.
Groupers are protogynous hermaphrodite and can change sex, an amazing ability to us but a relatively common occurrence among marine creatures. Some marine animals change from male to female, others (including groupers) change from female to male, and some organisms function as both sexes at one time.
A grouper will typically have a stout body with a larger mouth and it is not a very fast long-distance swimmer. Groupers prefer to ambush prey rather than chase after it. They are meat-eaters. Most eat fish, although the larger one also dine on crustaceans and even juvenile sea turtles, lobsters, crabs and octopus.
If you enjoy a large aquarium with fewer but larger fish, often with distinctive personalities, Groupers may be just the fish for you! They are mostly solitary fish, prefering their own company, and as allready said, they are predators!