Effect of water temperature on sex ratio and growth rate of juvenile Pelteobagrus fulvidraco , P. vachelli and hybrids [ P. fulvidraco (♀) × P . vachelli (♂)]

In order to explore the effect of water temperature on sex ratio and growth rate, we reared the juveniles of Pelteobagrus fulvidraco, Pelteobagrus vachelli and the hybrids from P. fulvidraco (♀) × P. vachelli (♂) at 6 different water temperature conditions (20, 23, 26, 29, 32 and 34 °C) in this study. The results showed the population of male and female fish at the ratio of 1:1 when the fish from three groups was cultured at water temperatures of 26, 29, 32 and 34 °C for 45 days. The analysis for the ratio between male and female reared at various temperatures suggests that the sex differentiation in P. fulvidraco, P. vachelli and the hybrids was not temperature-dependent sex determination (TSD). Based on the mathematical relationship between weight gain (WG) and water temperature, the maximum growth rate of P. fulvidraco, P. vachelli and the hybrids was achieved at 27.53, 28.36 and 28.40 °C, respectively. There is only very negligible difference between temperatures for the highest weight gain determined through mathematical modeling. However, weight gain determination shows comparatively higher growth rate at all test temperature. We initially deduced that the hybrids from P. fulvidraco (♀) × P. vachelli (♂) have heterosis. Our results indicated that the hybrids were very suitable for commercial aquaculture. Keywords: Hybrid, Yellow catfish, Water temperature, Sex ratio, Growth