This study investigates the effect of pawpaw seed meal using various level of inclusion in regulating procreation in Oreochromis niloticus (gift strain) via morphology (percentage defective sperm cells) as well as gonads using biomarkers. The pawpaw seed powder was compounded to a 2mm tilapia feed at 35% crude protein at 2, 4 and 6g per kg diet. A total of twenty (20) fi ngerlings (10 males and 10 females) with average weight of 20g were randomly allotted in triplicate into concrete ponds (1m x 1m x 1 0.8m) of 600 litres capacity with control. The Tilapia fi sh was nourished at 4% body weight per day in dual portions at 09.00 -09.30 hours and 17.00 -17.30 hours.The experiment lasted for 60 days. Minor tissue damage (testes) was observed in fi ngerlings fed PSM at a level of 2h/kg while disintegration of a lot of cells occurred at increased dietary levels of PSM (4g and 6g per kg diet) which resulted to lack of spermatids and oocytes in the fi sh testes. Hence, it is useful in battling diffi culties of overpopulation of tilapia in fi sh pond. Aside infertility, there were no observable contrary effect from pawpaw seeds consumption. Therefore, safe usage of 6 g PSM per kg diet for sixty (60) days is recommended for economic effi ciency of fi sh farms. Further research is required on reducing the antinutrient substances (carpaine) in pawpaw seed so that it can be safely use as an additive in feeds.