Protogynous sex change in ricefield eel Monopterus albus (Zuiew, 1793) by hormonal induction using javanese chili extract (Piper retrofractum Vahl)

Abstract

The ricefield eel Monopterus albus (Zuiew, 1793) is a protogynous hermaphrodite that undergoes sex change from female at the beginning of its life cycle to becoming male after going through the intersex phase. This study aims to evaluate the sex status of ricefield eels measuring 18–55 cm and the development of protogynous sex change by hormonal induction using Javanese chili extract (Piper retrofractum Vahl) through injection. One hundred and twenty eels averaged 24.86 ± 0.76 cm of length and 10.65 ± 0.83 g of weight was used in this research. A completely randomized experimental design consisted of four treatments (different doses of Javanese chili extract) and three replications were applied in this research. The dose of Javanese chili extract given was 187.5 g.kg-1 fish (P1) and 375 g.kg-1 fish (P2) compared to the control with injection using NaCl 3 mL.kg-1 fish (P0) and without injection (K). Injections through intramuscular were given 5 times with an interval of 7 days and observations of sex status were carried out every 14 days based on the development of the gonads. In the normal conditions, the sex status of ricefield eels measuring 20-33 cm in length indicates females, while intersex has a length ranging from 33–43 cm, and males with a length range of 43–55 cm. Hormone induction by injection of Javanese chili extract at a dose of ECJ 375 g.kg-1 fish produced a sex change percentage of eels with 75% male sex status and 25% intersex with an average length of 24.88 ± 0.35 cm and a weight of 10.22 ± 0.14 g.