UTTAR PRADESH JOURNAL OF ZOOLOGY

This paper investigates the optimal semen dilution and sperm-egg ratio for enhancing fertilization success in snowtrout (Schizothorax richardsonii). We achieved a high fertilization rate (98.80 ±0.13%) using undiluted semen, with a sperm concentration of 3.59 ±0.12x10⁸ sperm/ml, and sperm-egg-ratio of 29.5 ±0.09x10⁴ sperm/egg. At 1:4 and 1:10 dilutions, almost equally high fertilization rates of 98.73 ±0.11% and 97.06 ±0.11% were recorded, respectively. It reveals that almost 18,600 sperm/egg are required to achieve ~90% fertilization, while 26,900 sperm are essential for achieving ~97% fertilization with more than 75% motility. A ratio of 18,600 sperm/egg and 26,900 sperm/egg were obtained with 1:15 and 1:10 dilutions respectively, when one ml of diluted semen fertilized around 1200 eggs. Statistical analysis revealed that control and 1:4 dilution ratio were not significantly different (P ns, n=3). However, 1:4 dilution ratio was found significantly superior to other dilutions, viz. 1:10 (P<0.01, n=3); 1:15 (P<0.001, n=3) and 1:20 (P<0.001, n=3). Moreover, no correlation was established between spermatozoa motility and corresponding fertilization percentage. These findings have crucial implications for advancing artificial fertilization and selective breeding programs, conserving superior semen in gene banks, maximizing the judicious use of gametes in hatcheries, as well as enhancing our understanding of mating success.