Triggerfish are marine fish from the family Balistidae. Many are brightly colored and can grow quite large, with some species reaching up to 2½ feet in length. Some species of triggerfish feed on hard-shelled invertebrates and are not considered to be “reef safe.” Triggers are also known for being belligerent, and some keepers provide them a species tank of their own. Often marked by lines and spots, they inhabit warm coastal waters of the Atlantic, Mediterranean and the Indo-Pacific.

Anatomy and Appearance

Their size varies from 30 cm (1 foot) to 75 cm (2.5 feet).

Triggerfish have a roundish, laterally flat body with an anterior dorsal fin. They can erect the first two dorsal spines, the first one locks and the second one unlocks. This prevents predators from swallowing them or pulling them out of their holes. This locking and unlocking behaviour is why they are named 'triggerfish'.

They have a small pectoral fin, fused to one spine. Unlike the spine of a filefish, the spine of the triggerfish can be held in place by a second spine to make the fish more threatening to the predator. Their small eyes, situated on top of their large head, can be rotated independently. They have tough skin, covered with rough rhomboid-shaped scales that form a tough armour on their body. A big, angular-shaped head extends into a snout with strong jaws and sharp teeth, made for crushing shells. Each jaw contains a row of eight teeth, while the upper jaw contains another set of six plate-like teeth.

Behavior

Triggerfish are relatively poor swimmers, most of the time they move by undulating wave motions of the dorsal and anal fins, only using the tail fin for emergencies!

Triggerfish have teeth that are very stong and often stick out, which is ideal for eating shelled invertebrates and sea urchins. Don't put a Triggerfish in an aquarium with invertebrates! When eating a Crown of Thorns starfish, the trigger will first blow it over onto it's back in order to get at the soft unprotected underbelly.

Most are solitary and diurnal. They feed on hard-shelled invertebrates, a few feed on large zooplankton or algae. They lay their demersal eggs in a small hole, dug in the ground. Some species guard their eggs.

A few of the triggerfish species can be quite aggressive during reproduction season. In particular Picasso triggerfish and titan triggerfish viciously defend their circular nests against any intruders, including scuba divers and snorkelers. Their territory extends in a cone shape from the nest to the surface, so swimming upwards puts one further into the fishes' territory. A horizontal swim away from the nest site is the most sensible course of action when confronted by an angry triggerfish. In contrast to the relatively small Picasso triggerfish, the titan triggerfish poses a serious threat to inattentative divers due to its large size and powerful teeth.

Some species of triggerfish are known to make a sound akin to a grunt or snarl when taken out of the water.

Feeding

In captivity these fish will eat almost everything that is offered and should be fed everything like live foods (brine shrimp), frozen foods, flakes, squid, shrimp (regular or river), and even chopped earthworms.

Facts

Upper jaw non-protrusible.

Upper jaw usually with four teeth in outer and three in the inner series on each premaxillary.

Capable of rotating eyeballs independently.

Triggerfish normally swim by undulating their second dorsal and anal fins, but will use their tail for rapid bursts.

Most triggerfishes are solitary diurnal carnivores, feeding on a wide variety of invertebrates including hard-shelled mollusks and echinoderms; some also feed on algae or zooplankton.

They lay demersal eggs in a nest which is aggressively guarded by the female, less often by the male.

Popular and hardy in aquaria, but often aggressive.