The pond loach, also known as the Dojo loach, oriental weatherloach or oriental weatherfish, is a freshwater fish in the loach family Cobitidae. They are native to East Asia, but are also popular as an aquarium fish and introduced elsewhere in Asia and to Europe, America and Australia. The alternate name weather loach is shared with several other Cobitidae, including the other members of the genus Misgurnus and the spotted weather loach. This term comes from their ability to detect changes in barometric pressure before a storm and react with frantic swimming or standing on end.

Loaches are fish of the superfamily Cobitoidea. They are freshwater, benthic (bottom-dwelling) fish found in rivers and creeks throughout Eurasia and northern Africa. Loaches are among the most diverse groups of fish; the 1249 known species of Cobitoidea comprise about 107 genera divided among 9 families.