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.

Acanthurus monroviae
Acanthurus monroviae
Marine Fishes

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Acanthurus monroviae Steindachner, 1896

Common name: doctorfish

Synonyms and Other Names: Monrovia doctorfish

Taxonomy: available through www.itis.govITIS logo

Identification: Randall (1956, 2001) describes Acanthurus monroviae as having a deep and laterally-compressed body with the eye high on the head. The body is grey to brown with numerous irregular pale blue lines on the head and body oriented from the head to the tail. The upper edge of the gill covering has a yellow margin. The caudal fin curves deeply inward with a whitish posterior margin. A large bright yellow or orange spot is present on the caudal peduncle surrounding a caudal spine.

Size: This species of doctorfish can reach 45 cm standard length (Randall 2001).

Native Range: This species is found in the tropical Eastern Atlantic Ocean along the coast of West Africa from southern Morocco to Angola (Randall 2001).

Interactive maps: Point Distribution Maps

Nonindigenous Occurrences: One individual was photographed in a marine protected area off the coast of the São Paulo state in Brazil in 2002. The fish was observed schooling and feeding with the native doctorfish Acanthurus chirurgus (Luiz-Junior et al. 2004). A second individual was observed off the Santa Caterina state (Brazil) in 2015 (Anderson et al. 2015).

Ecology: Acanthurus monroviae is an herbivore that feeds primarily on algae (Randall 2001). It is restricted to areas with hard bottoms such as rocky shallow reefs (Randall 2001).

Means of Introduction: Unknown. Luiz-Junior et al. (2004) suggest the species may be a waif. Transatlantic dispersal may have been facilitated by rafting along with oceanic debris or hitch-hiking on transported oil/gas platforms (Pajuelo et al. 2016).  Alternately, the species may have been transported in the aquarium trade.

Status: Unknown.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: The sharp scalpel-like caudal peduncle spine found in members of the family Acanthuridae have the potential to deliver a painful slice. The spine serves to defend territory and prevent predation (Randall 2001). Many species in this family are popular aquarium fish.

References: (click for full references)

Anderson, A.B., A. Carvalho-Filho, R.A. Morais, L.T. Nunes, J.P. Quimbayo, and S.R. Floeter. 2015. Brazilian tropical fishes in their southern limit of distribution: checklist of Santa Catarina’s rocky reef ichthyofauna, remarks and new records. Check List 11:1688.

Luiz-Junior, O.J., S.R. Floeter, J.L. Gasparini, C.E.L. Ferreira, and P. Wirtz. 2004. The occurrence of Acanthurus monroviae (Perciformes: Acanthuridae) in the south-western Atlantic, with comments on other eastern Atlantic reef fishes occurring in Brazil. Journal of Fish Biology 65:1173-1179.

Pajuelo, J.G., J.A. González, R. Triay-Portella, J.A. Martín, R. Ruiz-Díaz, J.M. Lorenzo, and A. Luque. 2016. Introduction of non-native marine fish species to the Canary Islands waters through oil platforms as vectors. Journal of Marine Science 163:23-30.

Randall, J.E. 1956. A revision of the surgeon fish genus Acanthurus. Pacific Science 10:159-235.

Randall, J.E. 2001. Surgeonfishes of the World. Bishop Museum Press, Honolulu, Hawaii, USA.

Other Resources:

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

Revision Date: 9/10/2020

Peer Review Date: 9/8/2020

Citation Information:
Brown, M.E., and Schofield, P.J., 2021, Acanthurus monroviae Steindachner, 1896: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=3586, Revision Date: 9/10/2020, Peer Review Date: 9/8/2020, Access Date: 10/28/2021

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 [10/28/2021].

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