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.

Gymnocorymbus ternetzi
Gymnocorymbus ternetzi
(black tetra)

Copyright Info
Gymnocorymbus ternetzi (Boulenger, 1895)

Common name: black tetra

Synonyms and Other Names: Tetragonopterus ternetzi Boulenger, 1895

Taxonomy: available through www.itis.govITIS logo

Identification: Géry (1977) provided an identification key and color photographs. Color photographs were also provided in Axelrod et al. (1985) and Sakurai et al. (1993).

Size: 5-7.5 cm SL

Native Range: Tropical America. Amazon (Guaporé drainage) and La Plata (Paraguay River) basins in southern Brazil, Argentina, and Bolivia, South America (Géry 1977).

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 Gymnocorymbus ternetzi are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
CO198619861San Luis
FL197819791Little Manatee
LA200420041Liberty Bayou-Tchefuncta

Table last updated 7/25/2024

† Populations may not be currently present.

Means of Introduction: The Colorado introduction resulted from an escape from a local tropical fish farm, and the Florida record may represent either an aquarium release or a fish farm escape. The Louisiana collection took place near a tropical fish farm and was likely and escapee.

Status: Failed in Colorado, Florida, and Louisiana.

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: This is a well-known species among aquarists. The hot springs area of Colorado where this fish was found is at an altitude of 8,000 ft and has very cold winters, but L. Zuckerman (personal communication) suggested that some introduced species might spread downstream during warmer months and reach other thermal refugia.

Voucher specimens: Florida (UF 87974, 97058). The Colorado specimens were reportedly deposited with the U.S. Fish and Wildlife Service, Fort Collins (Zuckerman, personal communication). Zuckerman's Colorado collections were later transferred to the University of New Mexico, Albuquerque; however, Gymnocorymbus did not appear in a 1995 list of deposited fishes provided by the collections manager.

References: (click for full references)

Axelrod, H.R., W.E. Burgess, N. Pronek, and J.G. Walls. 1985. Dr. Axelrod's atlas of freshwater aquarium fishes. Tropical Fish Hobbyist Publications, Inc., Neptune City, NJ.

Courtenay, W.R., Jr., and D.A. Hensley. 1979. Survey of introduced non-native fishes. Phase I Report. Introduced exotic fishes in North America: status 1979. Report Submitted to National Fishery Research Laboratory, U.S. Fish and Wildlife Service, Gainesville, FL.

Géry, J. 1977. Characoids of the world. Tropical Fish Hobbyist Publications, Inc., Neptune City, NJ.

Piller, K. - Southeastern Louisiana University.

Zuckerman, L. - Aquatic Ecologist, Kansas Department of Wildlife and Parks, Pratt, KS.

Zuckerman, L.D., and R.J. Behnke. 1986. Introduced fishes in the San Luis Valley, Colorado. Pages 435-452 in R.H. Stroud, ed. Fish culture in fisheries management. Proceedings of a symposium on the role of fish culture in fisheries management at Lake Ozark, MO, March 31-April 3, 1985. American Fisheries Society, Bethesda, MD.

FishBase Summary

Author: Leo Nico, and Pam Fuller

Revision Date: 1/31/2005

Peer Review Date: 1/31/2005

Citation Information:
Leo Nico, and Pam Fuller, 2024, Gymnocorymbus ternetzi (Boulenger, 1895): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=420, Revision Date: 1/31/2005, Peer Review Date: 1/31/2005, Access Date: 7/25/2024

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 [7/25/2024].

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