Foureye Butterflyfish, Chaetodon capistratus
Foureye Butterflyfish, Chaetodon capistratus. Underwater photograph taken in coastal waters of Yal-Ku, Quintana Roo, April 2017. Photograph courtesy of Juan Rojo, Akumal.
Foureye Butterflyfish, Chaetodon capistratus. Underwater photographs taken in coastal waters off Bonaire, December 2019. Photographs courtesy of Bob Hillis, Ivins, Utah.
Foureye Butterflyfish, Chaetodon capistratus. Underwater photographs taken with coastal waters off Cozumel Island, Quintana Roo, March 2021. Photographs and identification courtesy of Marina Sutormina, Stockholm, Sweden.
The Foureye Butterflyfish, Chaetodon capistratus, is a member of the Butterflyfish or Chaetodontidae Family, and is known in Mexico as mariposa ocelada as well as isabelita. The Butterflyfishes are reef fishes and some of the most colorful tropical fishes in the ocean. Globally, there are ninety-three species of butterflyfish, of which ninety-two are found in the genus Chaetodon, with five found in Mexican waters, four in the Atlantic and one in the Pacific Ocean.
The Foureye Butterflyfish has a body profile shaped as a strongly compressed oval disc. This fish is named for the spot on its tail, which acts as a false eye. Adults are pale yellow with a gray bar from the nape to a crest through the eyes and thin black chevron lines from the top to the bottom on the sides pointing towards the head. They have a large black spot with a white ring under the rear of the soft dorsal fin. The anal and soft dorsal fins have 2 thick black stripes and the caudal fin is bright yellow with 2 thin bars. Juveniles are yellow with a black bar through the eyes, a gray bar from the spiny dorsal to the base of the pelvic fins, a gray bar from the soft dorsal to the anal fin base, and 2 black ocelli found on the soft dorsal fin and just below it on the body. The head has a short pointed snout with a concave forehead and a small projecting mouth equipped with long slender teeth set in bands of 6 to 7 rows on each jaw. The anal fin has 3 prominent spines and 16 or 17 rays with the second spine being longer than the third; and, their dorsal fin has 13 prominent spines and 18 to 20 rays. The rear margins of the anal and dorsal fins are bluntly angular and the caudal fin is rounded. They are covered with large rough scales. Their lateral line is incomplete.
The Foureye Butterflyfish are found in pairs within shallow rocky and reef areas at depths up to 20 m (65 feet). Juveniles are found closer to shore as solitary individuals around mangroves and seagrass beds. They reach a maximum of 15 cm (5.9 inches) in length. They are a diurnal species and feed on algae and benthic invertebrates during daylight hours. At night they hide trying to avoid predation by moray eels, various sharks, and larger fishes. The spot on the back is thought to act as a distraction pattern to confuse predators who like to attack the head. They are strong swimmers capable of maneuvering through coral reefs with ease by swimming sideways or upside down. Reproduction is oviparous in monogamous pairs that mate for life. Each female releases between 3,000 and 4,000 small pelagic eggs that quickly settle to the bottom and hatch within a day. The Foureye Butterflyfish is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
The Foureye Butterflyfish is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean. It is the most common butterflyfish in the Caribbean.
The Foureye Butterflyfish is similar in body profile to the eight other butterflyfish found in Mexican waters but is straightforward to identify due to the large black spot under the dorsal fin which gives rise to its common name.
From a conservation perspective the Foureye Butterflyfish is currently considered of Least Concern with stable and widely distributed populations. The major concern for its long-term survival is related to habitat degradation and loss of the coral reefs in which it resides. They are sold commercially by the aquarium trade due to their small stature and attractiveness but can be difficult to maintain. They present a challenge to divers as they retreat rapidly from encounters.