A plain olive-brown fish with a squared-off tail, grazing algae off rock in the shallows, up to 30 cm (12 in). Unremarkable to look at, and one of the most consequential fish in this sea.
Watch a pair for a minute and something odd shows up. Rabbitfish feed in twos, and while one puts its head down into the turf, the other stops eating and holds position facing outward, watching. Then they swap. Fish were not supposed to do this - taking turns at a cost to yourself, so a partner can eat safely, is behavior we file under primates and birds - and it was documented in these unremarkable grazers.
The spines are the other thing. Thirteen in the dorsal fin, seven in the anal, each grooved and venomous, and a sting is out of proportion to the size of the fish. They are folded flat while it swims and go up the moment it is cornered, which is why the injuries happen to hands in nets and buckets.
And it travels. This species went north through the Suez Canal (🇪🇬 Egypt) and is now one of the two rabbitfish that dominate the eastern Mediterranean, where it grazes algal forests down to bare rock. What is an ordinary reef herbivore here rewrote an entire sea over there.
The species. Siganus luridus (Rüppell 1829) - pale yellow. ETYFish
- plain dark olive-brown body with fine pale speckles, no stripes
- squared-off tail, unlike the forked tail of its striped relative
- small mouth held low for grazing
- almost always in a pair, the two fish rarely more than a meter apart
- length up to 30 cm
