Whats That Fish?

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The human race is generally a bit, dare it be said, ‘uneducated’ with regards to the ocean and all that she holds. Leisure Boating will look at different ocean species every month with the aim of giving our readers a closer look at the wide range of life forms that lurk below.


The Giant Trevally goes by many names, including Giant Kingfish, Lowly Trevally, Barrier Trevally, Ulua, or simply and perhaps most popularly, GT. It is a member of the Jack family, Carangidae, and is one of the most popular gamefish among sports fishermen. The GT can be found throughout the tropical and subtropical waters of the Indian and Pacific Oceans, ranging as far as Hawaii in the east to South Africa in the west, and from Japan in the north to Australia in the south.

As most gamefish do, the GT grows relatively fast, reaching sexual maturity at a length of around 60 cm at three years of age. But even an immature fish will give big game anglers a good run for their money. It is similar in shape to a number of other large Jacks and Trevallies but it can be distinguished by its steep head profile. It is silver in colour with occasional dark spots and males may become black once they’ve matured. The upper jaw contains a series of outer canines with an inner band of smaller teeth, while the lower jaw contains a single row of conical teeth. The GT is a semi-pelagic fish that roams throughout the water column, but is mostly demersal in nature – meaning it lives and feeds near or on the seabed. They commonly move between reef patches, often over large expanses of sand and mud bottoms between reefs. Older fish have been found to move to deeper seaward reefs and drop-offs away from the protection of fringing reefs, often to depths greater than 80 m. However, according to a paper in the Fishery Bulletin, larger individuals often return to these shallower waters as they patrol their ranges, often to hunt and reproduce.

Juvenile GT are known to enter and inhabit the upper reaches of rivers, coastal lakes and estuaries in several locations, one of them being South Africa…


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