Motan fish (Thynnichthysthynnoides) is one of the fish most found in the lake of Petai. This research was conducted in March until May 2019. Samples were captured using net. Sampling is done 5 times in 3 months. The reproductive biology aspects measured were sexual characteristics, sex ratio, gonadal maturity level, gonadal maturity index, fecundity, and egg diameter. The sample is 109 tails (7…