2006 NORTHEASTERN NATURALIST 13(1):39–42 First Records of Oriental Weatherfish (Misgurnus anguillicaudatus) in Maryland Matthew Ashton1 and Patrick Ciccotto1,* Abstract - We report the discovery of the non-native loach Misgurnus anguillicaudatus (Oriental Weatherfish) from two streams in Maryland in the vicinity of the Baltimore metropolitan area. Although only two individuals have been observed since 2007, a ban on this species in Maryland should be enacted to prevent it from becoming established in the state. Misgurnus anguillicaudatus (Cantor), commonly known as Oriental Weatherfish or Dojo Loach, is a member of the loach family (Cobitidae) and native from Burma north to Siberia in eastern Asia. Oriental Weatherfish have been introduced across multiple continents mainly through the aquarium trade and also for other purposes including live bait and for human consumption (Franch et al. 2008, Tabor et al. 2001). The species was first introduced into the United States in the early 20th century probably as aquarium or pet shop escapees, where it has since become established in several states, including Alabama, California, Hawaii, Idaho, Illinois, Indiana, Louisiana, Michigan, New Jersey, New York, Oregon, and Washington (Lee et al. 1980, Simon et al. 2006, Tabor et al. 2001, US Geological Survey 2004). Oriental Weatherfish were observed at two localities in the Patapsco River basin near the metropolitan area of Baltimore, MD. Fish collections were made with backpack electroshockers following Maryland Biological Stream Survey (MBSS) protocols (Stranko et al. 2007). The first observation occurred on 18 June 2007, and consisted of a single individual (137 mm, standard length) collected in Gwynns Falls, just west of the Baltimore city limits (39.36044°N, 76.74462°W). This specimen is currently housed at the North Carolina State Museum of Natural Sciences (NCSM 23879). No additional specimens were observed during a second visit to this locality in August 2007. A mixture of riffle/run and pool habitats comprised the 75-m stream segment sampled, with substrates ranging from silt and sand, to cobble and boulders. The second observation occurred on August 19, 2009 in the Patapsco River, approximately 1.6 river km downstream of Daniels Dam, west of Baltimore city (39.31618°N, 76.80188°W). A single individual (112 mm, standard length) was observed in a 75-m stream segment dominated by pool/glide habitat with a mixture of silt, sand, gravel, and cobble substrates and is currently stored at the Maryland Department of Natural Resources in Annapolis, MD. The individual was collected from a silted pool with coarse woody debris. Oriental Weatherfish are typically observed in muddy bottomed, still- or slowmoving habitats, both in its native and introduced ranges (Logan et al. 1996, Tabor et al. 2001). Benthic macroinvertebrates, including insect larvae and snails, comprise the majority of Oriental Weatherfish’s diet (Lee et al. 1980). These habitat types and dietary items were present at both sites where Oriental Weatherfish were observed. Water temperatures in native Oriental Weatherfish habitats have been reported to range from 10–25 °C (Simon et al. 2006). At the Gwynns Falls locality, the average daily summer water temperature was approximately 22 °C (data collected from 1 June–31 August 2007 with an Onset HOBO Water Temp Pro v2 data logger), suggesting that summer water temperature may not be a limiting factor Notes of the Northeastern Nat u ral ist, Issue 17/4, 2010 671 1Maryland Department of Natural Resources, 580 Taylor Avenue, Annapolis, MD 21401. *Corresponding author - pciccotto@dnr.state.md.us, 672 Northeastern Naturalist Notes Vol. 17, No. 4 to its introduction. Based on the documented life history of Oriental Weatherfish, there is the potential for this species to become established in Maryland, where ecological conditions are similar to other US states where it has become established. Despite suitable ecological conditions, only two individuals at two separate localities have been documented to date, and there is no evidence that this species has established wild naturally reproducing populations. While the source of these individuals in Maryland is difficult to determine, their proximity to the urban area of Baltimore is similar to the introductions of other non-native species, notably the invasive crayfish Orconectes virilis Hagen (Virile Crayfish), which was also first introduced in Maryland into the Patapsco River (Schwartz et al. 1963). Oriental Weatherfish have been observed in several aquarium stores as well as in grocery stores specializing in the sale of Asian foods in the Baltimore metropolitan area (M. Ashton and P. Ciccotto, pers. observ.). Little information has been recorded on the impacts of Oriental Weatherfish on biological communities where it has been introduced. Keller and Lake (2007) documented reduced macroinvertebrate populations as well as elevated ammonia, nitrate/ nitrite, and turbidity levels as a result of Oriental Weatherfish benthic feeding behavior. There is also the potential for the species to introduce parasites and diseases, compete with native fishes, and prey upon fish and amphibian eggs (Franch et al. 2008, Tabor et al. 2001). Although the ecological impacts are not fully understood, bans on the import of Oriental Weatherfish should be enacted to prevent the establishment and potential negative impacts of this non-native species in the aquatic systems of Maryland. Acknowledgments. We thank Jay Kilian, Andrew Becker, Scott Stranko, and the MBSS crew members involved in the collections of this species and associated habitat information. Literature Cited Franch, N., M. Clavero, M. Garrido, N. Gaya, V. López, Q. Pou-Rovira, and J.M. Queral. 2008. On the establishment and range expansion of Oriental Weatherfish (Misgurnus anguillicaudatus) in NE Iberian Peninsula. Biological Invasions 10:1327–1331. Keller, R.P., and P.S. Lake. 2007. Potential impacts of a recent and rapidly spreading coloniser of Australian freshwaters: Oriental Weatherloach (Misgurnus anguillicaudatus). Ecology of Freshwater Fish 16:124–132. Lee, D.S., C.R. Gilbert, C.H. Hocutt, R.E. Jenkins, D.E. McAllister, and J.R. Stauffer, Jr. (1980 et seq.) Atlas of North American Freshwater Fishes. North Carolina State Museum of Natural History, Raleigh, NC. 854 pp. Logan, D.J., E.L. Bibles, and D.F. Markle. 1996. Recent collections of exotic aquarium fishes in the freshwater of Oregon and thermal tolerance of Oriental Weatherfish and Pirapatinga. California Fish and Game 82:66–80. Schwartz, F.J., R. Rubelmann, and J. Allison. 1963. 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