The sex ratio in spawning can affect the efficiency and success of hatchery activities because sex ratio in spawning affects the number of eggs, the degree of fertilization, and the degree of hatching of eggs. Until now, there is limited research conducted in Corydoras paleatus fish spawning thus this study aims to determine differences in the reproductive performance of C. paleatus with different male sex ratios. This study uses three treatments, which are the ratio of fish male and female (1:1), (2:1), and (3:1). Each treatment uses one female fish. The vessel used in fish spawning is an aquarium with a size of 50 × 25 × 30 cm3. Spawning lasts for seven days and eggs are collected every day at 08.00. The number of eggs and larvae produced was not significantly different between treatments. Larvae produced by C. paleatus were 2,154 fish or 538 fish per female per week. The ratio (1:1) was considered an appropriate ratio in spawning C. paleatus fish because it has a high efficiency value.