Canthigaster valentini (Bleeker, 1853)
Blacksaddle or model toby, 11cm

This species is moderately rare at Kwajalein, and appears to usually inhabit the seaward slope at depths of 15m and greater. Like other puffers, it is extremely toxic. This sharpnose puffer serves as the model for a filefish mimic, Paraluteres prionurus. The file is presumably protected from predation by its resemblance to the inedible puffer. However, here at Kwajalein the mimic filefish is a lot more common than the poisonous model, which is not the way Batesian mimicry usually works. It is thought to be more effective if the dangerous model is more common, so that potential predators would learn more quickly to leave fish with this color pattern alone.

Below is the mimic Paraluteres prionurus filefish. One way to make certain which is which is to look at the second dorsal fin. In the file, the second dorsal fin runs continuously from about midbody to near the caudal peduncle. (The first dorsal is the hard spine just behind the eye, laid flat in the photo below.) In C. valentini, the dorsal fin is a smaller tuft, usually extending from right behind the third dorsal black saddle.

Created 22 October 2010
Updated 6 July 2020

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