Fish Identification Photos: Gulf Opaleye, Girella simpllicidens: The Gulf Opaleye is characterized by its overall dark brown-gray coloration, bright blue eyes, three or four white spots along its back below the dorsal fin base, and angular fin tips.

The Gulf Opaleye is almost identical to and can be easily confused with the California Opaleye, Girella nigricans (blunt anal and dorsal fins, only one or two white spots with blue-gray eyes). It is also quite similar in shape and appearance with 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 Gulf Opaleye is only found in the Sea of Cortez being very abundant in the upper half and rare in other locations. It 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 temperatures as low as 46 degrees and as high as 95 degrees Fahrenheit.

The Gulf Opaleye is a member of the Kyphosidae or Sea Chub, Nibbler, and Halfmoon Family. The Gulf Opaleye is a member of the subfamily Girellinae which are characterized by having loose movable teeth, and they lack teeth on the vomer.

The Gulf Opaleye is reported to reach 18 inches in length, up to 8 pounds in weight, and is found in the first 50-feet of the water column. It is a diurnal omnivore grazing on algae and preying on invertebrates.

Note: We do not at this time have a good quality photo of a Gulf Opaleye caught in Mexican waters, and request that anyone who has one, please send it to us here.