The Mastacembelidae are a family of fishes, known as the spiny eels. The Mastacembelids are part of the Order Synbranchiformes, the swamp eels, which are part of the Actinopterygii (ray-finned fishes). In an evaluation of the family in 2004, the subfamilies of Mastacembelidae were found to not be well supported and were rejected. Also, the genera Caecomastacembelus and Aethiomastacembelus were placed in synonymy with Mastacembelus. In some areas these fish are regarded as food fish. Several species of Mastacembelidae are aquarium fish, such as the fire eel.