Water quality and Catfish (Clarias batrachus) production in selected ponds of Siwan district

This study compared variation in water quality and fish growth for catfish (Clarias batrachus; 47g/fish) stocked in pond 1 (5.6 fish/m2, 14,820/ha) and in pond 2 as 12.6 fish/m2 density to 210 day study period. Feed input and culture environment affected water-quality dynamics. In pond 1, phytoplankton uptake predominated and little nitrification occurred, whereas in the pond 2 phytoplankton uptake and nitrification maintained low ammonia-nitrogen concentrations. Size classes of fish were skewed toward the larger market sizes in pond 1 and toward smaller market sizes in the pond 2 during the study period. Mean final fish weight was 630g/fish in pond 1 and 542g/fish in the pond 2 system. Despite these differences, fish yield was higher in the pond 2 system (7.7kg/m3 v. 1.5kg/m3) because of the greater initial stocking rate.