Eel culture can be done with a minimum investment, using locally available and cheap resources. The system of raising eels cal also be made environment-friendly.
Eels are long snake-like fishes with a smooth slimy scaleless skin. There are thousands of this kind in the sea and hundreds in freshwater. Monopterus albus (ricefield eel), which became instinct for unknown reasons was introduced by the International Institute of Rural Reconstruction (IIRR) in the late 80′s. Many farmers are raising this species for food. Updated info here