Photo by Mika d’Eau
The titan triggerfish can reach a length of up to 75cm (30in),for 7,2kg 16lbs and is the largest species of triggerfish in its range
They obtain their name from the locking mechanism used to hold the dorsal spine in place. The main dorsal spine is kept erect by a second spine which locks the dorsal spine in place.
Only when this trigger spine is moved can the main spine be lowered. The spine is used for defensive purposes because when raised it makes it difficult for a larger predator to swallow them. The spine is also used to lock the fish into crevices or small spaces making it difficult for predators to extract them. Triggerfish are adept at sliding into small thin crevices at night and their dorsal spines are then erected to lock them into place.
The titan triggerfish is solitary and found during the day (diurnal). It has been observed being aggressive to other fish who enter their territory.Though titan triggerfish are usually friendly to divers and snorkelers, females can be territorial and aggressive around their nests during the reproduction season, which occurs for about a week in each month (either after the full moon or new moon, depending on the population).
The nest is placed in a flat sandy area, and is defended vigorously against any intruders. The territory around the nest is roughly cone-shaped and divers who accidentally enter it may be attacked. Divers should swim horizontally away from the nest rather than upwards which would only take them further into the territory. Although bites are not venomous, the strong teeth can inflict serious injury that may require medical attention.
The threat posture includes the triggerfish facing the intruder while holding its first dorsal spine erect. It may also roll onto its side, allowing it a better look at the intruder it perceives as threatening its nest. The titan triggerfish will not always bite, but can swim at snorkellers and divers escorting them out of their territory.
Luckily titan triggerfish are not especially aggressive in the Maldives.
The titan triggerfish have a very varied diet and feeds on sea urchins, molluscs, crustaceans, tube worms and coral during the day. It often feeds by turning over rocks, stirring up sand and biting off pieces of branching coral, sometimes destroying a hard coral to access the crustaceans hiding inside. This is why other smaller fish species are often seen around it, as they feed on the detritus and smaller organisms that are stirred up. Titan triggerfish are one of a number of species of fish which can hunt and eat the crown-of-thorns starfish. Their rabbit-tooth-like large teeth and powerful mouth are used to crush their prey.
They are found in lagoons and at reefs to depths of 50 m (160 ft) in most of the Maldives and the rest of the Indo-Pacific.
Breeding with Triggerfish takes place between one male and a single female. The females lay their eggs on the substrate and they are fertilized by the male. The eggs are then guarded by the female to prevent them from being eaten by predators. While the female is guarding the eggs, their behaviour can be very aggressive.
