Groupers are members of the Serranidae family. They are the real sea basses. Members of Serranidae family typically have opercles (gill covers) with three spines; one main spine with a lesser spine above and below. Groupers can attain up to 3 m maximum length and weights of up to 400 kg.
The name "grouper" comes from the Portuguese name "garoupa" for the fish. In Malaysia and Indonesia, it is called "kerapu". Contrary to their name which suggests the fish stays in group, they are actually the solitary type. Unlike snappers which move in groups, they are intolerant of the same species or other similar fishes. Most species gather together in pairs or aggregations only for spawning. Many species are hermaphrodites, meaning that they can change their sex. They start out as females and change to male at a later stage.
Groupers are mostly demersal (benthic or bottom-oriented) fishes of tropical and subtropical areas, ranging from shallow coastal waters to moderate depths; the great majority of species occur in less than 200 meters. They are usually found over coral reefs, and rocky bottoms along the coasts.
Typical groupers have a stout body and a large mouth. They do not have many teeth on the edges of their jaws, but they have heavy crushing tooth palates inside they pharynx. Their mouth and gills form a powerful sucking system that can suck their prey in from a distance. They habitually eat fish, squid, and crustacean. They swallow prey rather than biting pieces of it and that makes them easy to get hook by bait. Normally a squid bait can be used over and over again.
Their colouration and ability to change hues and shades to blend in with their surroundings allow them to camouflage and lie in wait for prey rather than chasing in open water. They will ambush, dash and strike the prey in short distance. Right after they suck the bait, they will normally go into the rocks or structure that is surrounding them. When threatened, they use their mouth to expand their gill covers digging them into rock cave sides to form their shelters. Their gill muscles are so powerful that it is very difficult to pull them out of a cave.
There are 64 genera and approximately 521 species worldwide. Malaysia is represented by 15 genera and approximately 68 species.