This research aims to determine the reproductive potential of medaka fish (Oryzias profundicola) including fecundity, egg diameter, gonado somatic index (GSI). This research was carried out from January to June 2022. The sampling location was Lake Towuti, South Sulawesi. Medaka fish sample collection was carried out at each research station using a modified bag seser net with a mesh size of ¾ inch with a total length of one fishing gear unit of 15 meters a height of 1.50 meters and a bag length of 3 meters.
The fecundity of medaka fish at station 1 (Tanjung Timbala) ranged from 27-87 eggs (56 ± 15 eggs) for TKG III and 65-175 eggs (104 ± 21 eggs) for TKG IV, as well as total fecundity (15,157 eggs). Station 2 (Tanjung Lengkobutangan) fecundity for TKG III ranged from 31-84 eggs (47 ± 11 eggs) and TKG IV ranged from 97-182 eggs (153 ± 20 eggs), and total fecundity (11,369 eggs). The diameter of medaka fish eggs in Lake Towuti at all stations was found to range between 0.03-1.19 mm with the highest frequency for TKG III in the range 0.03-1.08 mm, while for TKG IV in the range 0.15-1. 19 mm. The IKG tendency for female fish is relatively greater than that of male fish, except in April and May at station 3 (Tanjung Bakara) and in April at station 5 (Tanjung Tominanga). Reproductive potential is the product of the number of fish and the average fecundity. The reproductive potential of medaka fish at station 1 is 15,157 eggs, station 2 is 11,369 eggs, station 3 is 10,723 eggs, station 4 is 14,842 eggs, and station 5 is 18,385 eggs.