The eel-tailed catfish, Tandanus tandanus, is a species of catfish (order Siluriformes) of the family Plotosidae. This fish is also known as dewfish, freshwater catfish, jewfish, and tandan. This species is a freshwater fish native to the Murray-Darling river system of eastern Australia. The scientific name for eel-tailed catfish comes from a name for the fish in an unidentified Aboriginal Australian language - Tandan - which Major Thomas Livingston Mitchell recorded on his 1832 expedition.