Monopterus albus was found in the swamp area of the Sawah Village. To understand the type of reproductive biology of M. albus, a study has been done in March-May 2018. Parameters measured were sex ratio, gonad maturity level, gonad somatic index (GSI), fecundity and egg diameter. Fish sampling were conducted 10 times, once/ week. There were 71 females, 15 transitions and 10 males captured. Sex …