Crescent Damselfish, Neopomacentrus cyanomos

Crescent Damselfish, Neopomacentrus cyanomos. Fish caught from coastal waters off Boca Raton, Florida, June 2023. Length: 10.1 cm (4.0 inches). Catch, photograph and identification courtesy of Chris Moore, Peoria, Arizona.

Crescent Damselfish, Neopomacentrus cyanomos. Fish caught from coastal waters off Boca Raton, Florida, June 2023. Length: 10.2 cm (4.0 inches). Catch, photograph and identification courtesy of Brayden Moore, Peoria, Arizona.

The Crescent Damselfish, Neopomacentrus cyanomos, is a member of the Damselfish or Pomacentridae Family, that is also known as the Regal Demoiselle and in Mexico as damisela crscienta and damisela real. Globally, there are fifteen species in the genus Neopomacentrus, with only this species being found in the Atlantic Ocean.

The Crescent Damselfish has an elongated oblong compressed body with a depth of 41% to 44% of standard length, thus similar in stature to a freshwater bluegill. They are a uniform dark brown color with some fishes having indistinct blue spots on the back and lower body, a large oval black spot with a green iridescence on the top corner of the gill cover at the origin of the lateral line. Their anal and pelvic fins are brown to whitish-brown; their causal fin is dark brown with a white to yellowish crescent along the center and rear edge; their dorsal fin is dark brown with a dark rear filament and a prominent white to yellow blotch a t the rear that extends out along the rear boarder of the fin; and, their pectoral fins are translucent with a dark spot at the top of the base. Their anal fin has two spines and 10 to 12 rays with filamentous tips, their caudal fin is lunate with filamentous tips; their dorsal fin has 13 spines and 11 or 12 rays with filamentous tips; and their pectoral fins have 17 or 18 rays. They have teeth set in two rows on both jaws and 21 to 24 gill rakers. They are covered with large scales.

The Crescent Damselfish is a non-migratory species that is found oval coral heads, and both inshore and offshore reefs at depths up to 53 m (175 feet). They are known to form large aggregations that can number into the thousands around oil platforms. They reach a maximum of 12.5 cm (5.0 inches) in length). They are diurnal feeders primarily consuming zooplankton. Reproduction is oviparous with distinct pairing during breeding. The eggs are demersal and adhere to the substrate in which males guard until they hatch. The eggs hatch in four days and the larvae stage is pelagic with a duration of 17 to 19 days. The Crescent 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 Crescent Damselfish is endemic to the Indo-Pacific from East Africa, the Red Sea, and the Persian Gulf east to Vanuatu and New Caledonia, north to southern Japan, and south to Australia. It has been introduced and is now established in the Gulf of Mexico and the Caribbean and is currently found in coastal waters from the Texas border to Belize.

The Crescent Damselfish is most likely confused with the Brown Chromis, Azurina multrilineata (lacks the black blotch on the shoulder).

From a conservation perspective the Crescent Damselfish is currently considered to be of Least Concern with stable, widely distributed populations. They are utilized by the aquarium trade and can be reared in captivity. They have been negatively impacted by local habitat degradation including areas that practice dynamite fishing.