Exerpes asper, the Sargassum blenny, is a species of labrisomid blenny native to the Gulf of California and the Pacific coast of Baja California.

[2] The Sargassum blenny has two quite distinct dorsal fins.

The general colour is brown with patches of silver on the flanks and there are 2 blue eyespots on the posterior dorsal fin.

It is found among the fronds of floating Sargassum mats.

When threatened it tends to curl its head round near its tail and remain motionless, relying on its cryptic appearance to escape detection.