Fish Identification Photos: Bumphead Damselfish, Microspathodon dorsalis: The Bumphead Damselfish is a very easy fish species to identify due to the bump on its head.

Overall, the Bumphead Damselfish has a dusky dark grey brown coloration with slightly golden brown fins. The eyes have blue irises.

The Bumphead Damselfish cannot be easily confused with any other species due to its unique head profile. This fish is normally found in rocky shore areas just beyond the surge zone within the first 30 feet of the water column.

It is very aggressive when feeding and defending its territory. The Bumphead Damselfish reaches a maximum length of 12 inches.

In Mexican waters, the Bumphead Damselfish has a limited distribution, being found at the tip of Baja California, along the coast of the Mexican mainland south to Guatemala, and around all of the Mexican oceanic islands. It is absent from all parts of the Sea of Cortez except for a small colony found just north and south of  Empalme, Sonora, along the coast of the mainland.

The Bumphead Damselfish is a member of a group of small, very colorful reef fishes found throughout the subtropical and tropical regions of the world’s oceans that make up the Pomacentridae Family which are known in Mexico as castañetas and jaquetas.

These differ from nearly all other marine reef fishes by their possession of a single nostril that occurs on each side of the snout that is a blind pouch. They are omnivores, feeding on bethic algae, crustaceans, plankton, and fish eggs. Most of the Pomacentridae are strongly territorial and solitary fishes. Globally, there are a total of 321 species of the Pomacentridae known, of which 13 are found in Mexico's Sea of Cortez.

Bumphead Damselfish, Microspathodon dorsalis: Caught from shore utilizing standard surf gear, on frozen shrimp at Km. 21, Cabo Real, Los Cabos, Mexico. Size 12 inches and disproportionately heavy for it length. Description and photo courtesy of John Snow.