Culture of Striped Catfish Pangasianodon hypophthalmus through Net Cages in Carp Pond under varying Stocking Density

This study was conducted to determine optimum stocking density of Pangasianodon hypophthalmus (Pangasius) for cage culture system installed in carp pond and evaluate its impact on carp pond productivity. Pangasius fingerlings (weight 5.90 ± 0.26 g; length 85.9 ± 0.45 mm) were stocked in PVC net cages of size 2 m x 2 m x 1 m using varying stocking density viz., T1- 80 fishes/m², T2- 100 fishes/m², T3- 120 fishes/m² and T4-140 fishes/m² in five replicates. After 180d of culture period significantly (p<0.05) higher final weight 613.06 ±5.684 g; length 374.8 ±3.26 mm; net gain in length 288.9±3.139 mm; ADG (Aggregate daily weight gain) 3.36 ±0.032 g was observed in T1-80 fishes/m². However higher net gain in weight of 607.16 ±5.602 and SGR (specific growth rate) 2.58 ±0.009 were observed in T1- 80 fishes/m² but there was no significant difference (P>0.05) among T1, T2 and T3. Although higher FCE (Food conversion efficiency) 64.43 ±0.565 % and PER (Protein efficiency ratio) 2.15±0.019 and lower FCR (Food conversion ratio) of 1.55 ±0.014 were estimated in T1- 80 fishes/m² but there was no significant difference among the treatments. No significant effect was observed on survival. Significantly higher (p<0.05) yield of 136.26 ±1.033 kg was obtained in T4 - 140 fishes/m² but there was no significant difference with the yield (134.9 ±1.251) kg recorded in T3 (120 fishes m^-2). Significantly higher B:C ratio 1.42 ±0.013 was recorded in T3. So, looking to the growth, yield and B:C ratio stocking density T3(120 fishes/m²) is an optimum density level for higher economic returns. As far as nutrients and primary productivity is concerned significantly higher NO3-N of 2.23 ± 0.288 mg/L, PO4-P of 0.26 ±0.032 mg/L, GPP (Gross primary productivity) of 8.48 ±1.07 g C m²/d, NPP (Net primary productivity) of 5.71 ±0.776 g C m²/d and CR (Community respiration) of 2.76 ±0.353 g C m²/d were recorded in carp pond when pangasius culture through net cages was carried out. Consequently, carp fish production about 2480 kg/0.4 ha with lower FCR of 1.23 and higher B:C ratio of 2.06 was recorded which is about 30.60 per cent higher than the carp production of previous years when pangasius cultured were not accompanied.