Threebanded Butterflyfish, Chaetodon humeralis
The Threebanded Butterflyfish, Chaetodon humeralis, whose common Spanish name is mariposa muñeca, is a species in the Butterflyfish or Chaetodontidae Family, known collectively as peces mariposa in Mexico. The Butterflyfishes are reef fishes and some of the most colorful tropical fishes in the ocean. Globally, ninety-three species of Butterflyfish are known of which only four live in the Sea of Cortez. There are ninety-two fish that are found in the genus Chaetodon, five of which are found in Mexican waters, four in the Atlantic and one in the Pacific.
The Threebanded Butterflyfish has a strongly compressed oval disc that has a depth that is 62 to 66% of standard length. They are very distinctively colored with three black bands across a silvery white to yellowish brown body, one of which runs through the eye, and a caudal fin with three additional dark narrow bands. The head has a short pointed snout with a small terminal mouth that is equipped with long and slender teeth. Their anal fin has a bluntly angular rear margin and has 3 spines and 15 to 17 rays with the second spine being longer than the third; their caudal fin is straight or slightly rounded; and, their dorsal fin has a bluntly angular rear margin and has 13 spines, that increase to the fourth or fifth spine and then decrease in length, and 18 to 25 rays. Their lateral line is incomplete with a high arch and the body is covered with large rough scales.
The Threebanded Butterflyfish are found in pairs or in small schools in and around rocky areas near shore at depths up to 350 feet. They are known to enter estuaries and within mangroves and lagoons. They are known to school with the Pacific Spadefish, Chaetodipterus zonatus. They reach a maximum length of 26 cm (10.6 inches). They feed on algae and benthic invertebrates. Reproduction is oviparous.
In Mexican waters the Threebanded Butterflyfish is found in all waters of the Pacific and are more common along the coast of the mainland. They are the most common Butterflyfish in the Tropical Eastern Pacific.
The Threebanded Butterflyfish is most likely confused with the Barberfish, Johnrandallia nigrirostris (black bands on the snout, across the eyes and forehead, and along the base of the dorsal fin), and the Scythe Butterflyfish, Prognathodes falcifer (inverted black “V” upper body).
The Threebanded Butterflyfish is sold commercially for the aquarium trade. They are also of interest to divers. From a conservation perspective they are currently considered to be of Least Concern.
Threebanded Butterflyfish, Chaetodon humeralis. Fish provided by the commercial fishermen of Puerto Los Cabos, Baja California Sur, June 2009. Length: 8.0 cm (3.1 inches). Fish identification courtesy of H.J. Walker, Jr., Scripps Institution of Oceanography, La Jolla, CA.
Threebanded Butterflyfish, Chaetodon humeralis. Underwater photo taken in coastal waters off Buena Vista, Baja California Sur, June 2017. Length: 8.9 cm (3.5 inches). Photo courtesy of Bob Hillis, Ivins, UT.
Threebanded Butterflyfish, Chaetodon humeralis. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, July 2012. Length: 12.3 cm (4.8 inches).
Threebanded Butterflyfish, Chaetodon humeralis. Fish caught in coastal waters off Mazatlán, Sinaloa, October 2016. Length: 15.5 cm (6.1 inches). Photo courtesy of George Brinkman, Guelph, Ontario, Canada.