Reef fish classification

Most reef fish have bony or hard skeletons and fall into the scientific class Osteichthyes. These reef fish include the 'plate-sized' fish groupers, snappers, emperors and breams, and the dainty butterfly fish, the poisonous box and puffer fishes, the tiny gobies and the graceful seahorses.

Sweetlip emperor Photo: GBRMPA

Fish, such as tuna and marlin, do not live on the reef but in the open water and are called 'pelagic' fish. Pelagic fish are usually bigger and faster swimming. Some such as tuna have redder 'meat' (muscles) because they need more oxygen for energy to move fast. The oxygen is provided by red blood cells.

Sharks and rays are also reef fish, but are different to the bony fish because they have cartilaginous, rather then bony skeletons. Cartilage is softer and more flexible than bone - the flexible structure in human noses is cartilage. For more information see Sharks.