Growth and survival of Pangasius hypophthalmus in biofloc technology: effects of carbon:nitrogen ratios

Abstract:

We conducted a 90-day experiment to evaluate the effects of different carbon:nitrogen (C:N) ratios on the growth and survival of Pangasius hypophthalmus juveniles in biofloc technology (BFT) systems. Four treatments were tested: control (conventional system, 5% feeding rate, 30% daily water exchange), T₁ (C:N 15:1, 8% feeding rate, no water exchange), T₂ (C:N 20:1, 8% feeding rate, no water exchange), and T₃ (C:N 25:1, 8% feeding rate, no water exchange). Each treatment had three replicates.

T₃ (C:N 25:1) produced the highest final weight (110.56 ± 1.65 g), which was 46.1% higher than control (75.67 ± 1.45 g). Specific growth rate (SGR) was highest in T₃ (2.54 ± 0.08 %/day) and lowest in control (2.04 ± 0.06 %/day). Survival reached 98.0 ± 1.2% in T₃, while control had only 92.0 ± 2.1%. A clear dose-response relationship was observed: higher C:N ratios produced better growth and higher survival. We conclude that a C:N ratio of 25:1 in biofloc systems significantly improves growth performance and survival of Pangasius hypophthalmus under zero-water exchange conditions.