Effect of different milt extenders on sperm parameters, fertilization rate, embryo quality, and fry production traits in the African catfish (Clarias gariepinus)

The fertility indices of the African catfish (Clarias gariepinus) milt diluted in different extenders were investigated using four adult males and two adult females. There were four groups with three replicates each, comprising an undiluted fresh milt group (FM; Control) and three groups of different milt extenders: soya beans milk (SM), citrated egg yolk (CEY), and citrated water (CW). Each extended milt group was diluted at a 1:10 ratio and stored at 4 °C for 48 h prior to spawning. After milt extension, the milt pH, sperm motility and viability, and sperm concentration were determined daily for 7 days. The egg fertilization and hatchability rates, fry survival rate, embryo viability rate (at 8 h and 24 h), and fry gross biometry (13 days post-spawning) were evaluated. The results showed no significant difference (p>0.05) in the diluted milt pH of the different groups. The sperm viability, motility, and concentration significantly decreased (p<0.05) in all groups, although the CEY group had the highest values (p<0.05) compared to SM and CW treatments. No fertilization was observed in SM treatment. It was concluded that as a milt extender for the African catfish, chilled CW was similar to CEY with respect to fertilization, hatchability, and fry survival rates, while a higher fry body weight was obtained in CW compared to CEY. On the other hand, the chilled SM extender stored for 48 h was not suitable for producing fry due to unsuccessful fertilization.