The Titan Trigger Fish lives up to its name.
It is a giant among reef fish, reaching a length of 75cm (30 inches) and a weight of more than 8kg (20lbs).
Ordinarily solitary, and wary of humans, the females can be very aggressive when guarding a nest.
They have enormous teeth and a formidable bite, so scuba divers are very careful around these animals.
Venturing into a nesting area is likely to get a scuba diver attacked in a very aggressive fashion and a bite will often require medical attention.
Nesting females vigorously guard their nests with territorial behaviour against any creature that ventures into a cone shaped area above the nest.
Scuba divers are advised to swim horizontally away from a titan triggerfish to avoid and intended escape that takes them into a danger zone.
Vividly coloured and beautiful to watch, these fish will often go about their business without being disturbed by a respectful approach.
This scuba diver has come upon one munching away happily on a star fish, 20m (60 feet) beneath the surface.
The starfish sits on a ledge and the titan triggerfish has found a small cave nearby, allowing it to retreat into the cave to finish a mouthful, and then return to bite off another.
The triggerfish will eat mostly sea urchins and crustaceans.
They use a jet of water propelled from their mouth to flip the urchin over.
This technique exposes the vulnerable centre where the sea urchin's mouth is, allowing the triggerfish to bite it and kill it without being injured by the venomous spines.
This fish lives on a coral and rock pillar that extends almost straight up from the ocean bottom in Papua New Guinea.
The sea life on these reefs is stunning and the creatures are as varied and unique as anywhere else on earth.
Scuba diving opens up a world that the adventurous are lucky enough to experience.