Abstract

Monopterus albus, the rice field eel (Zuiew), it is under Synbranchidae family; Synbranchiformes order. It lives in the rice fields, swamps, and muddy ponds in different Asian countries. M.albus is a hermaphrodite and undergoes sex reversal naturally. Female are intersexes, they have both female and male sex organs with oocytes and spermatocytes in their gonads, and then they become males [1]. The sex reversal of M.albus normally happens after spawning when the eel grows to 35 to 45cm in length [2]. There are many researchers studied the principle of natural sex reversal in M.albus, one of these studies says that this process based on genetic switch-mechanism which the differentiation and maturation of female germ-cells would cease then the epigenesis of male germ-cells and the interstitial Leydig’s cells started, this sexuality shifting from female to male involve the stimulation of some regulators and the mediation of biochemical components and physiological events and environmental factors might also play a role in this series of events [3].