Young Golden Trevally are strikingly coloured, their gold and black striped garb showing from where their name comes. These young fish like to seek out large animals like sharks, groupers and dugongs for protection, acting as pilot fish. Sometimes they make a mistake and decide that a diver is the perfect companion. They will hover close to the tank for the entirety of a dive until the diver finally has to say goodbye and emerge from the water, leaving the fish to swim quickly back to the relative safety of the reef to wait for another passing prospect.
Juvenile Golden Trevally with Diver. Photo credit Jill Studholme.
Some young trevally prefer to live as symbionts among the tentacles of jellyfish. When not following larger animals, or living in a jellyfish, the fish shoal together.
Juvenile Golden Trevally. Photo credit Jill Studholme.
Golden Trevally live throughout the Indo-Pacific from the Red Sea to Baja California and South Africa. When mature they grow as long as 120 cm. You see them in deep lagoons and seaward reefs. They root about in the sand for invertebrates and fishes, the mouth forming a tube to suck up their food.
Adult Golden Trevally. Photo credit Kare Kare (CC BY 3.0).
Their scientific name, Gnathanodon speciosus, comes from the Greek – Gnathos which means jaw and odous which means teeth. Actually, the adults have no teeth at all. Speciosus is from the Latin meaning showy. This species is the only one in the Gnathanodon genus. The Golden Trevally has many other common names, including Golden pilot jack.
Shoal of sub-adult Golden Trevally. Photo credit Laszlo Ilyes (CC BY 2.0).
The Trevally family (Carangidae) contains around 140 species. Many have a metallic sheen on their skin, caused by numerous mirror-like platelets of guanine crystals which reflect light. Normally trevally hunt in schools, circling smaller fish and gradually tightening the circle – catching any fish that tries to escape. Our adult Golden Trevally snuffling about in the sand is an exception.
Juvenile Golden Trevally with Dugong. Photo credit Suzanne Challoner.
Class: Actinopterygii > Order: Perciformes > Family: Carangidae > Genus: Gnathanodon > Species: Gnathanodon speciosus