Overview:

The oriental weather loach is a ray-finned fish of the loach family, Cobitidae, which belongs to the Order Cyrpiniformes, which also includes carps and minnows.³ They are native to eastern Asia, from Siberia south to Vietnam, and including Japan.⁴ Weather loaches have been introduced to Hawaii and the continental U.S., Australia, Mexico, and parts of Europe.¹ This fish is commonly used for bait, as a food source, and as an aquarium fish (Dojo loach) - these are the most likely routes of introduction.² The activity level of the oriental weather loach increases as barometric pressure changes, hence the common name weatherfish/loach.²Weather loaches are highly tolerant of extreme conditions and marginal habitat. They can survive droughts by burrowing into mud or silt.⁴ They are also capable of air-breathing in low oxygen waters via an adaptation of the digestive tract.² Weather loaches tend to burrow into mud and leaf litter with just their heads sticking out.²The oriental weather loach exhibits many characteristics of a successful invader; broad environmental tolerances, flexible diet, high reproductive potential, and high survivorship.¹The oriental weather loach is considered established in the border states of Washington and Idaho, as well as some states bordering the Great Lakes.⁴
As of January 1, 2016, the possession, sale, or transport of this species in Alberta is unlawful under the Fisheries Act.

Habitat:

Oriental weather loach live and feed on or near the bottom of still or gently flowing freshwater. They prefer muddy or silty bottoms. Normal water temperature range is 5 to 25º C but can tolerate temperatures as low as 2º C and as high as 30º C. They can survive low oxygen concentrations.²

Identification:

Body-color is yellow-brown to brown mottled with darker greenish-gray to dark brown markings.³ The ventral surface is paler in color. The body is cylindrical (eel-like)² and commonly 15 cm long but can reach 28 cm.³ The mouth is small and bears five pairs of barbels around the thick, fleshy lips.²
Pectoral fins are triangular with a stout spine. The dorsal fin originates above the pelvic fin, is short, and has 9 soft rays. The pelvic fins have 6-7 rays and the anal fin 7-8 rays. Conspicuous fatty crests are resent along the ventral and mid-dorsal lines of the tail, just in front of the tail fin. There is a dark spot in the upper half of the tailfin.² The lateral line is very short and does not extend past the pectoral fins.¹
Males have larger pectoral fins and the second ray is long and thick. Females have fuller abdomens.¹ Males are smaller than females.⁵

Ecology:

Oriental weather loaches are batch spawners, releasing and fertilizing eggs several times during a season. Breeding males will clasp females by bending their body around the female. Females can release as much as 18,000 eggs in one batch, which the male then fertilizes.⁵ The fertilized eggs are scattered in the water and not guarded.²The weather loach is a generalist feeder which senses prey with its barbels.² They feed on benthic invertebrates, detritus, insects, and gastropods (snails).⁵

Economic Impacts:

Oriental weather loach compete directly with native fish for food and also prey on the eggs and larvae of native fishes.² The decline of native sportfish populations could have impacts on recreation and tourism. Declines in water quality caused by loaches could impact shoreline property values.

Environmental Impacts:

Weather loaches can cause significant reductions in macroinvertebrates and compete directly with native fishes for food resources. The loach may also compete with native fishes for shelter and spawning sites. Loach may prey on the eggs and juveniles of native fishers. The weather loach can also impact water quality via increased ammonia and nitrate levels and turbidity.²

Sociological Impacts:

The transformation of native aquatic communities results in the intrinsic loss of natural capital and enjoyment of natural areas.

Prevention:

Learn how to identify oriental weather loaches and how to prevent spread. Do not purchase or grow weather loaches. Never, ever empty your aquarium into natural water bodies.

Control:

Currently, there are no established control options for the oriental weather loach other than preventing introduction. If caught, oriental weather loaches should be killed and not released. Report any sightings.

References:

¹Datasheet report for Misgurnus anguillicaudatus (oriental weatherloach). Invasive Species Compendium. www.cabi.org/isc/datasheetreport?dsid=75075Accessed: January 10, 2017.
²Global Invasive Species Database (2017) Species profile: Limnoperna fortunei. Downloaded from www.iucngisd.org/gisd/species.php?sc=1537 on 16-01-2017.
³Misgurnus anguillicaudatus (Cantor, 1842) Pond loach. www.fishbase.ca/summary/3016.html Accessed: January 10, 2017.
⁴Nico, L., P. Fuller, M. Neilson, J. Larson, A. Fusaro, T.H. Makled, and B. Loftus. 2017. Misgurnus anguillicaudatus. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=498 Revision Date: 1/27/2016 Accessed: January 28, 2017.
⁵Robert E. Schmidt and Alec J. Schmidt. Observations on Oriental Weatherfish (Misgurnus anguillicaudatus), an Exotic Species in the Hudson River Valley, New York. Northeastern Naturalist 21(1):134-145. March 2014. www.researchgate.net/publication/269580403_Observations_on_Oriental_Weatherfish_Misgurnus_anguillicaudatus_an_Exotic_Species_in_the_Hudson_River_Valley_New_York. Accessed: February 5, 2017.

Resources

• Wikipedia - Wikimedia Foundation, Inc.
• Fact Sheet - Gulf and South Atlantic Regional Panel on Aquatic Invasive Species

Selected Images

Maps

Invasive Listing Sources

• Alberta Fisheries Act
• Everglades Cooperative Invasive Species Management Area
• Florida Invasive Species Partnership
• Maryland Aquatic Nuisance Species Plan
• Maryland Invasive Species Council - Invasive Species of Concern in Maryland
• Michigan’s Prohibited and Restricted Species
• Mid-Atlantic Field Guide to Aquatic Invasive Species
• Minnesota DNR invasive species list
• New Jersey Invasive Species Strike Team 2017 Invasive Species List
• New York Regulated and Prohibited Invasive Species - Prohibited
• Pennsylvania's Field Guide to Aquatic Invasive Species
• Wisconsin's Invasive species rule – NR 40

References