Common Name: Regal Demoiselle

Synonyms and Other Names:

regal damsel

Identification: Overall body coloration is grey. Yellow or white posterior margin of dorsal, anal and caudal fins. Black "ear" spot. Meristics for specimens collected in the southern Gulf of Mexico: Dorsal fin XIII (11-12); anal fin II (11-12), pector fin 17, lateral line scales 17-18 (González-Gándara and de la Cruz-Francisco 2014). Similar species: brown chromis (Chromis multilineata) distinguished by the presence dark spot at base of pectoral fin; and yellowtail reeffish (Chromis enchrysura) distinguished by lobed (not forked) tail and presence of bright blue streak from snout above eyes and across nape.

Size: to 9 cm TL (Allen 1991)

Native Range: Indo-West Pacific: Red Sea and East Africa to the Philippines, north to southern Japan, south to northern Australia and Melanesia (except Fiji) (Allen 1991).

This map only depicts Great Lakes introductions. Click here for Great Lakes region collection information Click here for the national map

Ecology: Females deposit adhesive demersal eggs on a hard substrate. Eggs are elliptical and attached by adhesive filaments (Setu et al. 2010). The male guards, fans, and culls the clutch. Courtship and spawning were described by Setu et al. (2010). Larvae spend 17-19 days in the plankton before settling (Thresher et al. 1989). Occupies coral reefs to 60 ft depth and consumes zooplankton (Allen 1991). Randall et al. (1990) reports that the species occurs in protected areas, such as lagoons and harbors.

Means of Introduction: Unclear. Possible aquarium release, although listed in González-Gándara and de la Cruz-Francisco (2014) as a ballast transfer. Robertson et al. (2016) provide a discussion on the improbability of ballast water or shipping-related translocation, and the likelihood of other potential introduction vectors. It is not a common aquarium fish, making the pet-release hypothesis questionable (although still possible).  Another more plausible but yet untested hypothesis is that the species hitch-hiked along with towed oil and gas platforms translocated from the native range. Robertson et al. (2018) analyzed potential pathways for introduction and determined that the most likely way the fish were introduced was as hitch-hikers on towed oil and gas platforms.

Status: Established in the southwestern Gulf of Mexico between Veracruz and Sisal (González-Gándara and de la Cruz-Francisco 2014; Robertson et al. 2016). Established in the northern Gulf of Mexico from Louisiana to the Florida panhandle.

Great Lakes Impacts:

Remarks: Johnston and Akins (2016) used oceanic water-flow models and life-history data to model temporal and geographic spead of N. cyanomos as part of an initial risk analysis. They found that oceanic current patterns in the southern Gulf of Mexico are unlikely to promote pelagic larval dispersal, helping to limit expansion out of the region. Robertson et al. (2016) organized volunteer dive surveys to examine the extent of distribution of N. cyanomos in the Gulf of Mexico: no individuals were found at Flower Banks Gardens, the Florida Keys, the northeastern tip of the Yucatán (Isla Contoy and Puerto Morelos), and eastern Colombia. Robertson et al. (2016) also used DNA barcoding to confirm the identity of fishes from Madagascar Reef as N. cyanomos.

References (click for full reference list)

Other Resources:
USGS/NAS Technical Species Profile

Author: Schofield, P.J., and Neilson, M.E.

Contributing Agencies:

Revision Date: 2/24/2022

Peer Review Date: 1/14/2016

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.