The shiner perch (Cymatogaster aggregata) is a common surfperch found in estuaries, lagoons, and coastal streams along the Pacific coast from Alaska to Baja California.

[2] Shiner perches are similar to tule perches, deep-bodied with a dusky greenish back and silvery sides that have a pattern combining fine horizontal bars with three broad yellow vertical bars.

Breeding males turn almost entirely black, the barred pattern being obscured by dark speckles.

They are one of the most common fish in the bays and estuaries of their range, favoring beds of eelgrass, and often accumulating around piers as well.

They are often found with parasitic isopods such as Elthusa californica feeding off of them from their opercular cavity of the gill chamber.