Bigeye Trevally

Bigeye Trevally (Caranx sexfasciatus)

The big eye trevally is a common predatory fish distributed throughout the Indo-Pacific, and found around inshore and offshore reefs and seamounts down to depths of 100m. They can be distinguished from other trevallies in having a dark second dorsal fin with a white tip, as well as a small black spot high up on their operculum (gill cover; located a few cm behind the eye). They grow up to 120cm in length and 18 kg in weight.

During the day you may see these fish in large schools (up to 1500 individuals!) moving slowly around various forms of structure, but at night they break off from the school to hunt. They eat a wide variety of fish, crustaceans and molluscs. This differs too many other trevallies, which are mainly diurnal (daytime) hunters.

Big eye trevally mature at around 42 cm in length, and they form large mating aggregations to reproduce. Pairs speedily break away from this aggregation and swim belly to belly to spawn. After successful spawning they will return back into the aggregation. These two photos were taken at the Tangalooma shipwrecks, where large schools of big eye trevally are always encountered under certain parts of the wrecks.