The grey triggerfish are widespread in the tropical and subtropical waters of all oceans, and one species, Balistes Capriscus, is also found in the Mediterranean, including the Adriatic. They are named after the shape of their second dorsal and anal fins, which resemble the arch of a crossbow. These fins sway from side to side when the fish swims, making it immediately recognisable. Secondly, the first dorsal fin is equipped with a snap mechanism and a safety block, just like the trigger of a crossbow. It is no coincidence that this fish is called a triggerfish in English. This fin consists of three thorny rays, with the first being much longer and larger than the other two. In calm situations, the fin remains in a pocket, but it can be suddenly extracted when needed, allowing the fish to resist being stuck between rocks or being swallowed by a predator.

The body is laterally compressed, the head is large and the mouth is equipped with a strong beak, which is well-suited to its diet of small invertebrates.

They are very territorial and can become aggressive towards divers who approach their nest too closely, even biting them. In Italy, particularly in the south where it is most widespread, the triggerfish is highly regarded for its meat. As it emits a sound similar to a grunt when caught, it is also commonly called a pig fish (pesce porco).