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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.

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Common name: Hart's rivulus

Taxonomy: available through www.itis.gov

Identification: Distinguishing characteristics and photographs were given by Huber (1992). The spelling for this species is sometimes given as Rivulus harti.

Size: 10 cm.

Native Range: Tropical America. Caribbean Slope drainages of Venezuela, South America, from Rio Aroa east to Rio San Juan; islands of Trinidad, Tobago, Grenada, and Margarita (J. E. Thomerson, personal communication).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

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

Ecology: Inhabits small pools, ponds, streams, and tributaries. Can access isolated waterbodies via terrestrial mobility over moist ground (Seghers 1978). Omnivorous: primarily feeds on insects and juvenile Poecilia reticulata. Can also jump up to 14 cm above water surface to reach prey on overhanging vegetation (Seghers 1978).

Means of Introduction: The California fish were first found in January 1967 (St. Amant 1970). This introduction was probably due to escape or release from a nearby fish farm.

Status: Locally established in California. The species was thought to have disappeared after 1969 (Shapavalov et al. 1981), but additional specimens were taken in 1990 (Courtenay et al. 1991; Swift et al. 1993).  Moyle (2002) appears to indicate that it is still present, although he says it is probably not permanently established.

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 first specimens from Imperial County were identified by C. Hubbs. The tropical fish farm, mentioned as the possible source of the introduction, has been defunct for many years (Shapovalov et al. 1981; Dill and Cordone 1997; Moyle 2002).

Voucher specimens: SIO 67-4

References: (click for full references)

Courtenay, W.R., Jr., D.P. Jennings, and J.D. Williams. 1991. Appendix 2: exotic fishes. 97-107 in Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea, and W.B. Scott. Common and scientific names of fishes from the United States and Canada, 5th edition. American Fisheries Society Special Publication 20. American Fisheries Society, Bethesda, MD.

Dill, W.A., and A.J. Cordone. 1997. History and status of introduced fishes in California, 1871-1996. California Department of Fish and Game Fish Bulletin, volume 178.

Huber, J.H. 1992. Review of Rivulus -- ecobiogeography, relationships. Cybium, Société Française d'Ichtyologie, Paris, France.

Moyle, P. B. 2002. Inland fishes of California. Second edition. University of California Press, Berkeley, CA.

Seghers, B.H. 1978. Feeding behavior and terrestrial locomotion in the cyprinodontid fish, Rivulus hartii (Boulenger). Internationale Vereinigung fur Theoretische und Angerwandte Limnologie 20:2055-2059.

Shapovalov, L., A.J. Cordone, and W.A. Dill. 1981. A list of freshwater and anadromous fishes of California. California Fish ad Game 67(1):4-38.

St. Amant, J.A. 1970. Addition of Hart's rivulus, Rivulus hartii (Boulenger) to the California fauna. California Fish and Game 56(2):138.

Swift, C.C., T.R. Haglund, M. Ruiz, and R.N. Fisher. 1993. The status and distribution of the freshwater fishes of southern California. Bulletin of the Southern California Academy of Science 92(3):101-167.

Other Resources:

Author: Leo Nico, Pam Fuller, and Matt Neilson

Peer Review Date: 6/28/2011

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.