The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Neopomacentrus cyanomos
Neopomacentrus cyanomos
(Regal Demoiselle)
Marine Fishes

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Neopomacentrus cyanomos (Bleeker, 1856)

Common name: Regal Demoiselle

Synonyms and Other Names: regal damsel

Taxonomy: available through www.itis.govITIS logo

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).

Interactive maps: Point Distribution Maps

Nonindigenous Occurrences: The first sightings in the southwestern Gulf of Mexico were on nearshore coral reefs near Coatzacoalcos, Mexico in 2013 (González-Gándara and de la Cruz-Francisco 2014). In 2014 and 2015, individuals were observed on reefs near Veracruz City, and at Madagascar Reef off the northwestern coast of the Yucatán Peninsula (Robertson et al. 2016). In 2017, the species was found in the northern Gulf of Mexico, including offshore Louisiana, Mississippi, Alabama and Florida (R. Robertson pers. comm.). In July 2019, they were recorded from various locations on the western side of Trinidad, possibly as the result of hitch-hiking on oil platforms transported from the Indo-Pacific (Robertson and Kingon 2019). In February 2021, indiviudals were observed at multiple locations in reefs off the southern coast of Aruba

A video showing the history of the invasion as well as live footage of a population of N. cyanomos is available here: http://zenodo.org/record/58455#.V5ZMdPkrKmU.  In this video, the fish are remarkably abundant around an oil-platform.  Video courtesy of N. Simoes and D. R. Robertson.

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Neopomacentrus cyanomos are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AL201720181Northern Gulf of Mexico
FL201720202Choctawhatchee Bay; Northern Gulf of Mexico
LA201620171Northern Gulf of Mexico
MS201720171Northern Gulf of Mexico
TX201720191Northern Gulf of Mexico

Table last updated 6/13/2021

† Populations may not be currently present.

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.

Impact of Introduction: Unknown, although competition with native damselfishes is suspected (González-Gándara and de la Cruz-Francisco 2014).

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 references)

Allen, G.R. 1991. Damselfishes of the World. Mergus Publishers, Melle, Germany.

González-Gándara, C., and V. de la Cruz-Francisco. 2014. Unusual record of the Indo-Pacific pomacentrid Neopomacentrus cyanomos (Bleeker, 1856) on coral reefs of the Gulf of Mexico. BioInvasions Records 3:49-52.

Johnston, M.W., and J.L. Akins. 2016. The non-native royal damsel (Neopomacentrus cyanomos) in the southern Gulf of Mexico: An invasion risk? Marine Biology 163:12. http://link.springer.com/article/10.1007/s00227-015-2777-7

Randall, J.E., G.R. Allen, and R.C. Steene. 1990. Fishes of the Great Barrier Reef and Coral Sea. University of Hawai'i Press, Honolulu, HI.

Robertson, D.R., O. Dominguez-Dominguez, B. Victor, and N. Simoes. 2018. An Indo-Pacific damselfish (Neopomacentrus cyanomos) in the Gulf of Mexico: origin and mode of introduction. PeerJ 6:e4328 https://doi.org/10.7717/peerj.4328

Robertson, D.R., N. Simoes, C. Gutiérrez Rodríguez, V.J. Piñeros, and H. Perez-España. 2016. An Indo-Pacific damselfish well established in the southern Gulf of Mexico: prospects for a wider, adverse invasion. Journal of the Ocean Science Foundation 19:1-17. http://www.oceansciencefoundation.org/josf19a.html

Robertson, D Ross, & Kingon, Kelly. (2019). The alien Indo-Pacific damselfish, Neopomacentrus cyanomos, at Trinidad. Zenodo. http://doi.org/10.5281/zenodo.3364568

Setu, S.K., T.T. Ajith Kumar, T. Balasubramanian, A.R. Dabbagh, and M. Keshavarz. 2010. Breeding and rearing of regal damselfish Neopomacentrus cyanomos (Bleeker 1856): the role of green water in larval survival. World Journal of Fish and Marine Sciences 2:551-557.

Thresher, R.E., P.L. Colin, and L.J. Bell. 1989. Planktonic duration, distribution and population structure of western and central Pacific damselfishes (Pomacentridae). Copeia 1989:420-434.

FishBase Summary

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

Revision Date: 3/26/2021

Peer Review Date: 1/14/2016

Citation Information:
Schofield, P.J., and Neilson, M.E., 2021, Neopomacentrus cyanomos (Bleeker, 1856): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=2936, Revision Date: 3/26/2021, Peer Review Date: 1/14/2016, Access Date: 6/19/2021

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.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2021]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [6/19/2021].

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