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.

Hypostomus sp. (watwata group)
Hypostomus sp. (watwata group)
(suckermouth catfish)

Copyright Info
Hypostomus sp. (watwata group)

Common name: suckermouth catfish

Identification: The genus Hypostomus is the largest in the family Loricariidae, containing over 130 species and many undescribed forms (Armbruster 2004). Several apparently different Hypostomus species have been collected in the United States but have not been definitively identified to species (Page and Burr 1991; Courtenay and Stauffer 1990). Distinguishing characteristics of the genus and a key to loricariid genera were provided by Burgess (1989) and Armbruster (1997); a rediscription of the genus and list of included species was presented in Armbruster (2004). Highlighting the serious need for additional taxonomic and systematic work, Armbruster (1997, 2004) concluded that it is difficult to identify most species in the genus, and that there is no unique characters to diagnose the genus. Photographs appeared in Burgess (1989) and Ferraris (1991). Hypostomus has officially replaced the generic name Plecostomus. The genus was included in the key to Texas fishes of Hubbs et al. (1991); several identifying traits were also given by Page and Burr (1991), although in a later edition (Page and Burr 2011) those authors indicate the difficulty of identifying specimens to species.

Hypostomus can be distinguished from Pterygoplichthys (another loricariid common in the aquarium trade that has often been misidentified as Hypostomus) by the number of dorsal fin rays (7 vs 9-14 in Pterygoplichthys). In Hawaii, introduced Hypostomus can be distinguished from the sympatric introduced Ancistrus cf. temminckii by rough bony plates present along the snout margin (vs. plates absent in Ancistrus; Sabaj and Englund 1999).

Native Range:
Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

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 Hypostomus sp. (watwata group) are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
HI199020052Maui; Oahu

Table last updated 2/24/2024

† Populations may not be currently present.

Means of Introduction: Aquarium release

Status: Established in Hawaii.

Impact of Introduction: Because of their abundance in Hawaii, introduced Hypostomus, Pterygoplichthys, and Ancistrus may compete for food and space with native stream species (Devick 1989; Sabaj and Englund 1999).

Remarks: Museum specimens: Hawaii (BPBM 38535, 38601; INHS 48305; UF 119858, 119998).

References: (click for full references)

Devick, W.S. 1989. Disturbances and fluctuations in the Wahiawa Reservoir ecosystem. Project No. F-14-R-13, Job 4, Study I. Division of Aquatic Resources, Hawaii Dept of Land and Natural Resources.

Mundy, B.C. 2005. Checklist of fishes of the Hawaiian archipelago. Bishop Museum Bulletins in Zoology, Number 6.

Sabaj, M.H. and R.A. Englund. 1999. Preliminary identification and current distribution of two suckermouth armored catfishes (Loricariidae) intrdouced to Oahu streams. Bishop Museum Occasional Papers 59:50-55.

Other Resources:
FishBase Summary

Author: Neilson, M.E.

Revision Date: 6/14/2019

Peer Review Date: 10/22/2013

Citation Information:
Neilson, M.E., 2024, Hypostomus sp. (watwata group): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=763, Revision Date: 6/14/2019, Peer Review Date: 10/22/2013, Access Date: 2/25/2024

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. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [2/25/2024].

Contact us if you are using data from this site for a publication to make sure the data are being used appropriately and for potential co-authorship if warranted.

For general information and questions about the database, contact Wesley Daniel. For problems and technical issues, contact Matthew Neilson.