The Asian Loach Invasion in New York State

     The Oriental weatherfish (Misgurnus anguillicaudatus) is a popular aquarium pet and lesser known as a food source or baitfish. Commonly referred to as the Dojo, Asian pond, weather, or Japanese/Chinese ‘loach’, etc.; it is a subtropical and temperate species native to Asia that has successfully invaded various waters in Europe, Australia, and the USA. Fishbase reports that the majority of its introductions are believed to be fish farm escapees resulting in unknown ecological impacts to native fishes and their communities. However, USA introductions are more likely from illegal aquaria release and food source stocking but very little has been written about wild loach in North America. Loach share many habitat and physiological similarities with another introduced Asian, the snakehead (Channa spp.). Both are cold hardy, facultative air breathers, prefer slow moving or stagnant waters, and considered valuable table fare by many Asians yet loach receive little press because they are not a predator like snakeheads.

     Prior to 2010, loach were recorded as established in three watersheds of New York State until the recent discovery of two new breeding populations in central New York. In both instances local landowners reported unusual catches in minnow traps baited with bread, which evidently is one of the most productive and least time consuming methods of harvesting loach. The source of these two infestations is unknown and remains under investigation. At least two of the five loach-infested watersheds located across New York State support multiple year classes  and three have been infested for decades. Field observations and laboratory work has revealed new information on its life history. Unfortunately, late discoveries of loach in several watersheds has probably resulted in range expansion and increased competition of space/food with natives. Successful eradication of loach in the wild may be impractical because of its similarities with snakeheads (inhabits wetlands, breathes air), unknown dispersal range, and continued illegal stocking. Preventing new introductions via education, public outreach, and timely law enforcement may be our only defense against the spread of loach and other alien fishes.