Evaluation of growth and water quality in pangasiid catfish (Pangasius hypophthalmus) monoculture and polyculture with silver carp (Hypophthalmichthys molitrix)

An experiment was carried out to evaluate the fish growth and water quality in pangasiid catfish (Pangasius hypophthalmus Sauvage) monoculture and polyculture with silver carp (Hypophthalmichthys molitrix Valenciennes) in nine (0.05 acre each) earthen ponds under three treatments each with three replications for a period of 98 days. In treatment 1 (Ti) 12000 pangasiid catfish per acre (2.47 acre = 1 ha), in treatment 2 (12) 6000 pangasiid catfish plus 6000 silver carp per acre and in treatment 3 (13) 8000 pangasiid catfish plus 4000 silver carp per acre were stocked. A commercial peileted feed containing 28% crude protein and 6% lipid was fed to the pangasiid catfish at the rate of 8%, 6% and 4%-of the body weight per day during the first month, second month and rest of the culture period, respectively. The growth of fishes was found significantly (p<0.05) different among the treatments. Highest growth of pangasiid catfish was found in T2 and lowest in T1, and in case of silver carp the growth was highest in 13. Among the studied water quality parameters dissolved oxygen, nitiatenitrogen, phosphate-phosphorus and phytoplankton cell density differed significantly (p<0.05). The dissolved oxygen was highest in 12 and lowest in Ti. The nitrate-nitrogen, phosphate-phosphorus and phytoplankton cell density were highest in Ti and lowest in T2. The results suggest that polyculture of pangasiid catfish and silver carp at the ratio of 1:1 with a total density of 12000 fishes per acre is suitable for good fish growth and better water quality maintenance.