A fish built as a triangular box with a hump on the ridge, sculling slowly over seagrass with fins that look far too small for it. Every part of the shape is a compromise the animal made in exchange for armor.
The body is a rigid case of fused bony plates. Nothing bends, so it cannot flex its way through the water and instead drives itself with the fins alone, hovering and pivoting like a small machine. That makes it slow, obvious and easy to approach, and it can afford to be, because a predator that bites one gets a mouthful of bone and a mouthful of poison.
Under stress it releases ostracitoxin from the skin, a soap-like poison that destroys the gills of other fish in a confined volume. In the sea it is diluted to nothing. In a bucket or a tank it kills everything present, including the cowfish.
It has also traveled. This is one of the Lessepsian migrants that went north through Suez, and it is now recorded across the eastern Mediterranean - an armored, poisonous, slow-moving box quietly extending its range through a canal.
Regional guides print it as the humpback turretfish, which describes it better than cowfish does: the spine on the ridge is the feature, and there are no horns on the head at all.
The genus. Tetrosomus Swainson 1839 - tetro- (four) + soma (body). ETYFish
The species. Tetrosomus gibbosus (Linnaeus 1758) - humpbacked. ETYFish
- triangular in cross section, with a sharp keel along the back
- tall spine or hump rising from the keel, especially in juveniles
- pale yellow-brown with fine blue-white spots
- sculls with tiny fins, hovering rather than swimming
- length up to 30 cm
Why it's threatened
Threat classification from the IUCN Red List.
