The relationships of female size with reproductive parameters, egg diameter and larval growth of striped catfish (Pangasianodon hypophthalmus)

Abstract

This study aimed to quantify relationships between female weight and some reproductive parameters, yolk sac volume, and larval length of striped catfish (Pangasianodon hypophthalmus). Mature fish were selected from the broodstock conditioning tank in a recirculating system. Females (n = 36) weighing 1.7 to 7.0 kg were artificially propagated with the same male group. The results showed that realized fecundity (331,667 - 1,404,791 eggs/female) was positively correlated (P < 0.01), while relative fecundity (73,849 - 255,214 eggs/kg female) had a negative relationship with females’ weight (P < 0.01). Eighteen females were divided into 3 groups of weights (6 - 7 kg, n = 5; 5 - 5.5 kg, n = 8; and 3 - 4.8 kg, n = 5) to examine other reproductive parameters. Egg diameter (1,014 - 1,024 µm), fertilization rate (65.78 - 79.00%), and hatching rate (42.73 - 57.27%) were not significantly different among female groups. Larvae produced by medium and large-sized females appeared to grow (in length) faster than those by small-sized females, and these differences were significant at hatching, 24, and 72 h post-hatch (P < 0.05). Yolk sac volume was not different among the three groups (P > 0.05), ranging from 0.37 to 0.41 mm3 at hatching, and decreasing 62.2 - 68.3% after 36 h and 83.8 - 85.4% after 48 h post-hatch. In sum, females weighing 5 to 7 kg had higher realized fecundity and better growth of larvae during the first five days compared to small females.