Common name: Spotfin Spiny Eel
Synonyms and Other Names: peacock eel, peacock spiny eel.
available through www.itis.gov
Identification: Elongate, eel-like fish with a compressed tail and a row of small spines along the back anterior to a soft-rayed dorsal fin; pectoral and anal fins present; no pelvic fins; snout is extended into a proboscis with anterior nostrils at the side (Kottelat 2001); 4-5 dark round spots on dorsal fin. Roberts (1980, 1986) provided keys to the genus. The elongated snout (or rostrum) containing tooth-bearing bony plates (Roberts 1980, 1986) distinguishes this genus from all others found in North America.
Size: To 200 mm SL (Kottelat 2001)
Native Range: Mekong basin in Laos, Thailand, Cambodia, and Vietnam; Chao Phraya basin (Rainboth 1996; Kottelat 2001).
Hydrologic Unit Codes (HUCs) Explained
Puerto Rico &
Interactive maps: Point Distribution Maps
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 Macrognathus siamensis are found here.
Table last updated 2/27/2023
† Populations may not be currently present.
Ecology: Occurs in benthic habitats in slow-moving streams and canals, standing pools or reservoirs, or in freshwater wetlands. Diet includes benthic crustaceans, annelids, and insect larvae (Rainboth 1996).
Means of Introduction: Presumed aquarium release.
Status: Established in Everglades National Park and sections of adjacent freshwater canals (Shafland et al. 2008; Kline et al. 2013).
Impact of Introduction:
Summary of species impacts derived from literature review. Click on an icon to find out more...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.
References: (click for full references)
Kline, J.L., W.F. Loftus, K. Kotun, J.C. Trexler, J.S. Rehage, J.J. Lorenz, and M. Robinson. 2013. Recent fish introductions into Everglades National Park: an unforeseen consequence of water-management? Wetlands. http://link.springer.com/article/10.1007/s13157-012-0362-0.
Kottelat, M. 2001. Fishes of Laos. WHT Publications (Pte) Ltd., Sri Lanka.
Rainboth, W.J. 1996. Fishes of the Cambodian Mekong. FAO Species Identification Field Guide for Fishery Purposes. Food and Agriculture Organization of the United Nations, Rome.
Roberts, T.R. 1980. A revision of the Asian mastacembelid fish genus Macrognathus. Copeia 1980(3):385-391.
Roberts, T.R. 1986. Systematic review of the Mastacembelidae or spiny eels of Burma and Thailand, with description of two new species of Macrognathus. Japanese Journal of Ichthyology 33(2):95-109.
Shafland, P.L., K.B. Gestring, and M.S. Stanford. 2008. Florida's exotic freshwater fishes - 2007. Florida Scientist 71(3):220-245.
Pam Fuller, and Matt Neilson
Revision Date: 8/23/2019
Peer Review Date: 4/30/2013
Pam Fuller, and Matt Neilson, 2023, Macrognathus siamensis (Günther, 1861): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=2261, Revision Date: 8/23/2019, Peer Review Date: 4/30/2013, Access Date: 6/6/2023
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.