The family is further divided into two subfamilies: Latilinae and Malacanthinae. Some authors regard these subfamilies as two evolutionarily distinct families.
Description
The two subfamilies appear to be morphologically different, with members of the Latilinae having deeper bodies bearing predorsal ridge and heads rounded to squarish in profile. In contrast, members of the Malacanthinae are more slender with elongated bodies lacking predorsal ridge and rounded head. They also differ ecologically, with latilines typically occurring below 50 m and malacanthines shallower than 50 m depth. Tilefish range in size from 11 cm to 125 cm and a weight of 30 kg. Both subfamilies have long dorsal and anal fins, the latter having one or two spines. The gill covers have one spine which may be sharp or blunt; some species also have a cutaneous ridge atop the head. The tail fin may range in shape from truncated to forked. Most species are fairly low-key in colour, commonly shades of yellow, brown, and gray. Notable exceptions include three small, vibrant Hoplolatilus species: the purple sand tilefish, Starck's tilefish, and the redback sand tilefish. Tilefish larvae are notable for their generous complement of spines and serrations on the head and scales. This feature also explains the family name Malacanthidae, from the Greek words mala meaning "many" and akantha meaning "thorn".
Habitat and diet
Generally shallow-water fish, tilefish are usually found at depths of 50–200 m in both temperate and tropical waters of the Atlantic, Pacific, and Indian Oceans. All species seek shelter in self-made burrows, caves at the bases of reefs, or piles of rock, often in canyons or at the edges of steep slopes. Either gravelly or sandy substrate may be preferred, depending on the species. Most species are strictly marine; an exception is found in the blue blanquillo which is known to enter the brackish waters of Papua New Guinea's Goldie River. Tilefish feed primarily on small benthic invertebrates, especially crustaceans such as crab and shrimp. Mollusks, worms, sea urchins, and small fish are also taken. After the 1882 mass die-off, great northern tilefish were thought to be extinct until a large number were caught in 1910 near New Bedford, Massachusetts.
Behaviour and reproduction
Active fish, tilefish keep to themselves and generally stay at or near the bottom. They rely heavily on their keen eyesight to catch their prey. If approached, the fish quickly dive into their constructed retreats, often head-first. The chameleon sand tilefish relies on its remarkable ability to rapidly change colour to evade predators. Many species form monogamous pairs, while some are solitary in nature, and others colonial. Some species, such as the rare pastel tilefish of the Indo-Pacific, actively builds large rubble mounds above which they school and in which they live. These mounds serve as both refuge and as a microecosystem for other reef species. The reproductive habits of tilefish are not well studied. Spawning occurs throughout the spring and summer; all species are presumed not to guard their broods. Eggs are small and made buoyant by oil. The larvae are pelagic and drift until the fish have reached the juvenile stage.
Tilefish from the Gulf of Mexico have been shown to have high levels of mercury, and the FDA has recommended against their consumption by pregnant women. Atlantic Ocean tilefish may have lower levels of mercury and may be safer to consume.
