Yellowtail Damselfish
Yellowtail Damselfish, Microspathodon chrysurus. Underwater photographs taken with coastal waters off Cozumel Island, Quintana Roo, March 2021. Photographs and identification courtesy of Marina Sutormina, Stockholm, Sweden.
The Yellowtail Damselfish, Microspathodon chrysurus, is a member of the Damselfish or Pomacentridae Family, that is also known as the Caribbean Jewel Damsel and the Jewel Damselfish and in Mexico as jaqueta coliamarilla. Globally, there are five species in the genus Microspathodon, of which three are found in Mexican waters, one in the Atlantic and two in the Pacific Ocean.
The Yellowtail Damselfish has a deep oblong thick compressed body. Adult and young adult damselfish differ significantly in terms of body color. Adults are yellowish-brown with a bright yellow caudal fin. Young adults are violet with blue spots in their back and a transparent caudal fin. Their heads have a small protrusible mouth that opens in the front with a single row of teeth. Their anal fin has 2 spines and 12 or 13 rays; their caudal fin is bluntly forked; and their dorsal fin has 12 spines and 14 or 15 rays. They have 13 to 16 gill rakers on their lower arch. Their lateral line is incomplete and ends under the edge of their dorsal fin base. They are covered with large rough scales.
The Yellowtail Damselfish are a common territorial non-migratory species that reside within coral reefs at depths up to 120 m (400 feet) but normally within the first 10 m (30 feet). The juveniles are found among branches of yellow stinging coral, Millepora. Adults are found in very shallow waters, usually near top of outer edge where there are caves, holes, fire coral and dead coral is abundant. They reach a maximum of 21 cm (8.3 inches) in length. The adults primarily consume blue-green algae primarily; the juveniles are carnivorous consuming nematocysts and zooxanthellae. Juveniles occasionally pick parasites from other species of fish. The adult males are known to practice cannibalism on their young. Reproduction is oviparous with pairing of individuals; eggs are distributed demersal and adhere to the substrate due to their stickiness. The males aerate and vigorously defend the eggs. The Yellowtail Damselfish 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 Yellowtail Damselfish 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.
The Yellowtail Damselfish are most likely confused with Dusky Damselfish, Stegastes adustus (adults with gray-brown caudal fin; juveniles do not have spots) and the Purple Reeffish, Chromis scotti (adults with brown tail; juveniles without spots).
From a conservation perspective the Yellowtail Damselfish is currently considered to be of Least Concern with stable, widely distributed populations. They are utilized by the aquarium trade and a minor level and they are retained for consumption by artisanal fishermen. Their long term viability is assured as they have raised in captivity.