Effect of Different Stocking Densities on the Water Quality Parameters in Cyprinus carpio var. communis Culture System

Abstract

The present study evaluated the effect of different stocking densities on selected water-quality parameters in the culture medium of common carp, Cyprinus carpio var. communis. The experiment was conducted for 90 days using four stocking-density treatments: T₁ (3.7 kg m⁻³), T₂ (6.9 kg m⁻³), T₃ (9.3 kg m⁻³) and T₄ (11.7 kg m⁻³), with four replications in a completely randomised design. Common carp fingerlings with an average initial weight of 30 g were reared in 80 L plastic tubs and fed daily at 5% of body weight. Water-quality parameters were assessed fortnightly during the experimental period. Temperature ranged from 24.05 ± 0.04 to 27.70 ± 0.04 °C, while dissolved oxygen remained between 8.20 ± 0.07 and 8.57 ± 0.02 mg L⁻¹. Free carbon dioxide ranged from 0.62 ± 0.02 to 0.65 ± 0.04 mg L⁻¹, and pH remained slightly alkaline, ranging from 7.42 ± 0.04 to 7.65 ± 0.06. Nitrite-nitrogen (NO₂-N) varied from 5.82 ± 0.02 to 5.90 ± 0.00 µg L⁻¹, whereas ammoniacal nitrogen ranged from 49.00 ± 0.00 to 49.10 ± 0.02 µg L⁻¹. The findings indicate that, under the conditions of this study, the assessed stocking densities maintained water-quality parameters within acceptable limits for common carp culture.