Triggerfishes are about 40 species of often brightly colored fish of the family Balistidae. Often marked by lines and spots, they inhabit tropical and subtropical oceans throughout the world, with the greatest species richness in the Indo-Pacific. Most are found in relatively shallow, coastal habitats, especially at coral reefs, but a few, such as the aptly named oceanic triggerfish (Canthidermis maculata), are pelagic. While several species from this family are popular in the marine aquarium trade.
For example, take a fish Picasso and its scientific name Rhinecanthus aculeatus.
Scientific classification as follows:
The largest member of the family, the stone triggerfish (Pseudobalistes naufragium) reaches 1 metre (3.3 ft) but most species have a maximum length between 20 and 50 centimetres.
Triggerfish have an oval shaped, highly compressed body. The head is large, terminating in a small but strong- jawed mouth with teeth adapted for crushing shells. The eyes are small, set far back from the mouth, at the top of the head. The anterior dorsal fin is reduced to a set of three spines. The first spine is stout and by far the longest. All three are normally retracted into a groove. The anal and posterior dorsal fins are capable of undulating from side to side to provide slow speed movement. The sickle shaped caudal fin is used only to escape predators.
Some of the fish, such as trigger (Odonus niger) feeds on plankton, and some feeds on crustaceans, others feed on algae.
The trigger fish known level of intelligence as it is unusual among fishes, and they have the ability to learn from previous experiences (McDavid, J. (2007). Aquarium Fish: Triggerfish).
Some types Treasure to be very aggressive when protecting their eggs. Both Picasso (Rhinecanthus aculeatus) and Titan Treasure (viridescens Balistoides) defend their nests fiercely against intruders, including scuba divers and snorkelers. (Millington, J.T .; Randall, J.E. (1990). “Triggerfish bite)
Watch the video to see the aggressive behavior of the fish: