Filefish are marine fish belonging to the order Tetraodontiformes and family Monacanthidae. They are close cousins to triggerfish and sometimes also listed under the same family of Balistidae. There are roughly 31 genera, including Aluterus, Amanses, Cantherhines, Chaetoderma, Monacanthus, Oxymonacanthus, Paraluteres, and Pervagor, and about 103 species of filefish. They live in warm seas all throughout the Atlantic, Pacific and Indian Oceans, especially waters near Australia. Some species like the scrawled filefish can swim as deep as 400 feet, but they’re usually found frequenting shores and at depths of 10 to 60 feet deep.
Filefish bodies are flat, oval and deeply keeled. The eyes are high on their head and snouts are prominently projected. Their pelvic fins may either be rudimentary, or absent with just a bony protruding knob. The caudal fins are short and fan-shaped. Filefish fin rays are not branched at the ends. They almost appear scaleless because their scales are so small. But their rough skin has a velvety or sandpapery feel that lends to their name of “filefish.” Two dorsal spines, the first of which is long and usually barbed while the second is minute, serve as a way to escape from predators. Filefish will hide in crevices and erect the spines on their back and belly to wedge themselves into place, making it difficult to remove them. Some key differences between triggerfish and filefish, is that triggerfish have 3 dorsal fins, a tympanum and branched fin rays. Triggerfish are also the more likely of the two species to bite when threatened.
The mouths of filefish are small and flattened from side-to-side, but contain well-developed teeth. The upper has four teeth in an inner series and six in the outer series, while in the lower jaw there are four to six teeth in the outer series. They’ll use their incisors to break off pieces of coral they feed on and chisel holes into the shells of mollusks in order to extract softer parts. Filefish are omnivorous grazers with a diet including algae, phytoplankton, anemones, seagrass, hydrozoans, gorgonian coral and tunicate worms. Rather than being diurnal or nocturnal feeders like most fish, filefish hunt whenever food is plentiful. Common predators of filefish include mahi-mahi and Bluefin tuna. Copepods and worms are also known parasites of this fish. Filefish will breed in groups of one male and two to five females with the females laying demersal eggs in safe spots for the male to come along and fertilize. A male or female will stay to guard the fertilized eggs and attach intruders who get too close. Currently, filefish are not considered an endangered species. Humans don’t normally consume filefish due to the risk of ciguatera poisoning, though Korea does produce roasted filefish jerky as a snack food.