The rice field eel (Monopterus albus Zuieuw) belongs to the protogynous hermaphrodite. The demand for rice field eel increases throughout the year. One of the potential villages to cultivate the eel in Banyumas Regency is Babakan. However, people in the village have not done it due to lack of reproductive character information for the eel. This research was aimed to understand the reproductive characters of this eel (sex-based on body length and stages of gonad development along with Gonad Maturity Level (GML), Gonad Maturity Index (GMI), fecundity, egg diameter, the relationship between body length and GML as well as GMI. The method used was a survey with purposive sampling design. Sampling was done in the rice field of Babakan village, with an interval of 1 month, repeated four times, with 30 samples each. The results showed the eels caught experienced the intersex phase at 30.5–30.7 cm, the eel less than that length was female whereas that exceeded the length was male. The sex eels based on stages of gonad development was in GML-I (there were oocytes equipped with nucleus and cytoplasm),  GML-II (the presence of cortical alveoli stage), GML-III (was the stage of vitelogenesis), GML-IV (was a mature stage). The Intersex stage was characterized by the presence of degenerated oocytes and the presence of testicular lobes, and the male stage was characterized by a testicular lobe. The dominant GML in November were GML-I and GML-II, in December were  GML-I and GML-II, January was GML-III, March was GML-IV and male. Fecundity of eels reached 207 to 370 eggs with an average of 252 eggs. The egg diameter was 0.22–2.5 mm, indicating the eel was included in the batch spawner. The highest GMI of eels was in January, and the highest GMI was in the interval of 0.0017–0.0242 in the entire month of sampling. The eel body length was not correlated to GML, but correlated to the GMI.

Priyo Susatyo

Risa Umami

Sri Sukmaningrum