Bony fishesOsteichthyes

Bony fishes are vertebrates with skeletons primarily composed of bone. They display immense diversity in body shape, size, and colouration, with individuals ranging from under 1 cm (0.4 in) to several metres long. Their fins are supported by bony rays, and the body is typically covered in overlapping bony scales, though some species are scaleless. Gills are protected by a bony operculum, which allows respiration without constant swimming. Most also possess a swim bladder for precise buoyancy control.

Bony fishes inhabit all accessible marine environments, from shallow reef crests and lagoons to deeper offshore waters, commonly observed between 0 and 100 metres (0-330 ft). This is the most abundant and diverse group of fishes encountered by divers. Their diets are highly varied, including herbivores, carnivores, omnivores, and planktivores, with mouth shapes adapted to their specific prey. Behaviour patterns are equally diverse, ranging from solitary and territorial species to large, schooling pelagic forms.