Queen angelfish
The queen angelfish ("Holacanthus ciliaris"), also known as the blue angelfish, golden angelfish or yellow angelfish, is a species of marine angelfish found in the western Atlantic Ocean. It is a benthic (ocean floor) warm-water species that lives in coral reefs. It is recognized by its blue and yellow coloration and a distinctive spot or "crown" on its forehead. This crown distinguishes it from the closely related and similar looking Bermuda blue angelfish ("Holacanthus bermudensis"), with which it overlaps in range and can interbreed. Adult queen angelfish are selective feeders and primarily eat sponges. Their social structure  consists of harems which include one male and up to four females. They live within a territory where the females forage separately and are tended to by the male. Breeding in the species occurs near a full moon. The transparent eggs are pelagic and float in the water, hatching after 15–20 hours. Juveniles of the species have different coloration than adults and act as cleaner fish. The queen angelfish is popular in the aquarium trade and has been a particularly common exported species from Brazil. In 2010, the queen angelfish was assessed as least concern by the International Union for  Conservation of Nature as the wild population appeared to be stable. Taxonomy. The queen angelfish was first formally described as "Chaetodon ciliaris" in 1758 by Carl Linnaeus in the 10th edition of his "Systema Naturae", with the type locality given as the "Western Atlantic/Caribbean". It was moved to the genus "Holacanthus" by French naturalist Bernard Germain de Lacépède in 1802, the name of which is derived from the Ancient Greek words "holos" (full) and "akantha" (thorn). Its specific name "ciliaris" means "fringed", a reference to its "squamis ciliatis" ("ciliate scales"). Other common names for the species include "blue angelfish , golden angelfish" and "yellow angelfish". Marine angelfish of the genus "Holacanthus" likely originated between 10.2 and 7.6 million years ago (mya). The most basal species is the Guinean angelfish ("Holacanthus africanus") off the coast of West Africa, indicating that the lineage colonized the Atlantic from the Indian Ocean. The closure of the Isthmus of Panama 3.5–3.1 mya led to the splitting off of the Tropical Eastern Pacific species. The closest relative and sister species of the queen angelfish is the sympatric and similar Bermuda blue angelfish ("H. bermudensis"), which it split from around 1.5 mya. They are known to interbreed , producing a hybrid known as the Townsend angelfish which has features intermediate between the parent species. The Townsend angelfish is fertile, and individuals can breed both with each other and with the two parent species. The following cladogram is based on molecular evidence: Description. The queen angelfish has a deep, compressed oval-shaped body with a short, blunt snout and a small mouth containing bristle-like teeth. The dorsal fin contains 14 spines and 19–21 soft rays, and the anal fin has 3 spines and 20–21 soft rays. This species attains a maximum total length of and weight of . Males  may be larger than females. The species has blue-green flank (side) scales with yellow edges; the tail and paired fins are bright-yellow, and the anal fins are orange-yellow. The back of the dorsal fin is tipped in orange-yellow, and the pectoral fins have large blue spots at the base. On the forehead, above and behind the eyes, is an ocellated (eye-like) spot or "crown" with an electric blue ring surrounding a cobalt blue center with electric blue spots. This crown is the main feature distinguishing the species from the Bermuda blue angelfish. Juveniles are dark  blue with bright blue vertical stripes and a yellow pectoral area. They resemble juvenile blue angelfish and are distinguished by more curved vertical stripes. Growing juveniles develop transitional patterns as they reach their adult coloration. Seven other color morphs have been recorded off the coast of the Saint Peter and Saint Paul Archipelago, Brazil. These include a bright-orange gold morph, an all-white morph, a white morph with orange and black blotches, a bright blue morph that has a pale caudal fin, a yellow-faced bright blue morph with a pale caudal fin, a bright blue morph with both  the pectorals and caudal fin yellow, and a bright blue morph with black-and-white pectoral/caudal fins and white mouth and operculum. Another color morph was recorded off Dry Tortugas, Florida, in 2009. This fish was mostly cobalt blue with white pectoral, pelvic and caudal fins. The snout and operculum area had mottled cobalt blue and white coloration, and the dorsal and anal fins were deep yellow-orange and white. There are records of at least two wild queen angelfish at St. Peter and St. Paul with a "pughead" skeletal deformity, a compressed upper jaw and a protruded lower  jaw. Such abnormalities are more common in captive fish. Ecology. Queen angelfish are found in tropical and subtropical areas of the Western Atlantic Ocean around the coasts and islands of the Americas. They occur from Florida along the Gulf of Mexico and the Caribbean Sea down to Brazil. Their range extends as far east as Bermuda and the Saint Peter and Saint Paul Archipelago. Queen angelfish are benthic or bottom-dwelling and occur from shallow waters close to shore down to . They live in coral reefs and are typically encountered either as solitary fish or as pairs, swimming among soft  corals. Queen angelfish feed on sponges, tunicates, jellyfish, corals, plankton and algae. Juveniles act as cleaner fish and set up cleaning stations where they pick ectoparasites off bigger fish. Off St. Thomas Island and Salvador, Bahia, 90% of the diet of adults is sponges. Off the Saint Peter and Saint Paul Archipelago, more than 30 prey species may be consumed, 68% being sponges, 25% being algae, and 5% being bryozoans. Queen angelfish appear to be selective feeders as the proporation of prey in their diet does not correlate with their adundance. On the species level, the angelfish of the Saint  Peter and Saint Paul Archipelago prefer the less common sponges "Geodia neptuni", "Erylus latens", "Clathria calla" and "Asteropus niger". Life cycle. Queen angelfish live in harems consisting of one male and two to four females within a large territory. Little is known about the sexual development of the species, though they are presumed to be protogynous hermaphrodites. If a harem male disappears, the largest female may change sex. Around midday, the females forage separately in different locations. The male tends to each of them, rushing at, circling and feeding next to them. Spawning in this species occurs year-round. It  is observed sometime around a full moon. Courtship involves the male displaying his side to the female and slightly flicking his pectoral fins outwardly at intervals lasting a few seconds. At the beginning of spawning, the female ascends towards the surface as the male swims below her with his snout touching her vent. They then release their eggs and semen into the water. The female can discharge between 25 and 75 thousand eggs in an evening. After spawning, the pair separate and head for the bottom, where the female may nip and chase the male. The transparent eggs are pelagic  and float in the water, hatching after 15–20 hours. The initial larvae have a large yolk sac and lack functional eyes, gut or fins, but after 48 hours, the yolk is absorbed, and the larvae have more of a resemblance to fish. These larvae feed on plankton and grow rapidly. Between three and four weeks after hatching, when they have reached a length of , they settle on the floor as juveniles. They live alone and in territories in and around finger sponges and coral. Within these territories, juveniles establish cleaning stations for other fish. Human interactions. Queen angelfish are not  normally eaten nor are they commercially fished. They are captured mostly for the aquarium trade, where they are highly valued. As juveniles, angelfish can be conditioned to accept typical aquarium food and hence have a higher survival rate than individuals taken as adults, which would require a more specialized diet. The queen angelfish has been a commonly exported angelfish species from Brazil. From 1995 to 2000, 43,730 fish were traded at Fortaleza in the northeast of the country and in 1995, the queen and French angelfish were nearly 75% of marine ornamental fish sold. In 2010, the queen angelfish was  assessed as least concern by the International Union for Conservation of Nature, as the species is not fished much in its range (aside from Brazil) and the wild population appeared to be stable. Queen angelfish have been caught in the eastern Adriatic Sea, off Croatia, in 2011, and the Mediterranean Sea, off Malta, in 2020. These are likely introductions from the aquarium industry and not natural colonizations. In 2015, an aquarium-introduced angelfish was caught in the Red Sea at Eilat's Coral Beach, Israel. The disease-causing bacterium "Photobacterium damselae piscicida", which was not previously documented in Red Sea  fish, was isolated from its kidney, raising concerns that it could infect native fish.