A small tuna to 1 m (3 ft), steel-blue with a broken pattern of dark bands over the back and a few dark spots low on the flank. It hunts in fast schools along reef edges and in open coastal water, and it is the tuna a diver here is most likely to see rather than read about.
The scales tell the family story. Most of the body is smooth and scaleless, but a patch of larger scales forms a collar behind the head - the corselet - and it is a hallmark of the tunas: a compromise between drag and protection for a fish built to swim at speed continuously.
Like its larger relatives it is warm-bodied, holding heat generated by the swimming muscles instead of losing it through the gills, and it cannot stop moving without suffocating. It also cannot afford to stop eating: a school works schooling anchovies and small fish through the day.
It is fished heavily throughout the 🌊 Indian Ocean and appears in local markets constantly. Ciguatera has been reported from large individuals, which is unusual in a pelagic fish and worth knowing if the catch is eaten.
The genus. Euthynnus Lütken 1883 - eu- (true) + thynnus (tunny). ETYFish
The species. Euthynnus affinis (Cantor 1849) - related. ETYFish
- steel-blue back with a broken pattern of dark wavy bands above the lateral line
- several dark spots between the pectoral and pelvic fins
- patch of larger scales forming a corselet behind the head, rest of the body smooth
- length up to 1 m
