California Opaleye, Girella nigricans: The California Opaleye is characterized by its overall dark brown-gray coloration, grey-blue eyes, one or two white spots along its back just below the dorsal fin base, and blunt fin tips.
The California Opaleye is almost identical and can be easily confused with the Gulf Opaleye, Girella simplicidens (pointed anal and dorsal fins, three to four white spots with bright blue eyes). The California Opaleye is also quite similar in shape and appearance to the California Halfmoon, Medialuna californiensis (black blotch at top of gill cover and a concave caudal fin), and the Zebra Perch, Hermosilla azurea (eight faint bars on its sides and a black spot at the pectoral fin base).
The California Opaleye is a member of the Kyphosidae or Sea Chub, Nibbler, and Halfmoon Family which is made up of sea chubs, nibblers, and halfmoons, and is a member of the subfamily Girellinae which is characterized by having loose movable teeth and no teeth on the vomer.
In Mexican fishing waters, the California Opaleye has a limited distribution being found along the Pacific side of the Baja California peninsula south to Cabo San Lucas and in the upper two- thirds of the Sea of Cortez.
The California Opaleye is found in large schools roaming shallow rocky reef areas which have an abundance of algae growth. The species is eurythermal being able to tolerate water temperatures as low as 46 degrees and as high as 95 degrees Fahrenheit.
This fish species is reported to reach 24 inches in length, up to 10 pounds in weight, and is found in the first 100 feet of the water column. It is a diurnal omnivore grazing on algae and preying on invertebrates.