The reproductive patterns of Oryzias woworae Parenty & Hadiaty, 2010, the endemic fish of Muna Island, Southeast Sulawesi, Indonesia, in rearing with varied sex ratios

Abstract

The endemic freshwater ornamental fish Oryzias woworae Parenty & Hadiaty, 2010 is an endangered species, and the biological information is very rare. This research aims to study the effectiveness of sex ratio on reproduction in the limited number of broodstock. Research was conducted at RC for Limnology and Water Resources, BRIN Laboratory, in April 2022 for 3 weeks with two replicates. The sex ratio used (♂:♀) included (1:1)/A, (2:3)/B, and ( 2:5)/C. All treatments were 100% on the percentage of hatching to spawning (H/S). Treatments A & B had a fertilization rate of 100%, respectively. Meanwhile, treatment A had the highest hatching rate (91.88%). Treatment C had the highest score on the number of spawning and hatching, 5 ± 1.41 times, respectively; the average number of eggs per spawning (5.6±2.27); and the average number of larvae per hatching (4.8±1.23). However, this value is almost the same as the other treatments (A & B). For the effectiveness of using a limited number of broodstock, it is recommended to use the sex ratio 1:! for O woworae reproduction. Sex determination has been seen in the fish since the 14th of the week old. Male's size tends to be larger than female.