Triggerfish favour fairly shallow water, certainly no deeper than thirty metres. They feed on shellfish and crustaceans, using their small but extremely powerful jaws to crunch through the shells of the creatures they feed on. For this reason triggerfish are found around stony and broken ground which has a high population of shellfish, invertebrates and crabs for them to feed on.
Triggerfish get their name from their spiny dorsal fins. This fin is erected as a means of defence against predators. The first dorsal fin is raised and the second part of the dorsal fin fits into a groove to keep the spine raised up. The second part can be pressed down (like a trigger) to lower the spine. Divers have found triggerfish to be inquisitive and unafraid when approached. However, they can be territorial and aggressive, especially when guarding nests during breeding season. They can swim at divers and attempt to drive them away if they get to close to the nest. While the grey triggerfish found in UK and Irish waters are too small to harm humans the larger triggerfish found in tropical waters are more dangerous. The titan triggerfish (Balistoides viridescens) can attack divers and bite hard enough for the victim to require medical attention.
With triggerfish not common in the UK and Irish anglers often catch them when targeting other species. However, in areas around the south where trigger fish have been reported it can be worth specifically trying for a this species in the summer months. Deep water rock marks or piers which cast onto broken and rough ground are the top marks. Many triggerfish are caught on baits presented on the seabed, but deep float fished baits can also produce good results, especially if they are allowed to slowly drift around the area with the tidal flow where the triggerfish are feeding. In deep-water rock marks freelining down a bait can work, as triggerfish will come very close in to feed on both mussels and all kinds of shellfish which attach themselves to rocks.
When it comes to bait mussels and peeler crabs are the most obvious fish due to the triggerfish’s natural diet of shellfish and crustaceans. However, they are opportunistic feeders and other baits such as mackerel strip, ragworm and squid will also catch. Indeed, mackerel (being used to target other species) probably accounts for more triggerfish catches than any other bait. The trigger fish has a very small mouth so hook sizes should be kept correspondingly small at size 1 or 2.
Remember though that the triggerfish have powerful jaws and teeth, and is a decent fighter, so hook patterns should be kept strong and hooklengths made of 30lb monofilament line or stronger.