Vitellus utilization under concurrent variations in temperature and light intensity in Ussuri catfish, Pseudobagrus ussuriensis

The combined effects of temperature (18-34 degrees C) and light intensity (100-1,800 lx) on the vitellus utilization, duration of vitelline absorption and larval growth in Pseudobagrus ussuriensis were studied under laboratory conditions using a central composite design and response surface methodology. The results showed that the first- and second-order effects of temperature and light intensity were significant (p < 0.05), the interactive effect between temperature and light intensity was non-significant (p > 0.05) and the effects of light intensity were greater than that of temperature. Predicated on the reliable models of vitelline utilization regarding temperature and light intensity, the optimal rearing environment shaped by a temperature/light intensity of 25-26 degrees C/1,030 lx (12.98 mu mol m(-2) s(-1)) was obtained via model optimization. Verification results attained under laboratory conditions showed that vitelline utilization was most efficient at these optima. The application of the environmental optima would contribute to refining the seed quality in the larviculture of this species.