EFFECTS OF WATER TEMPERATURE AND FEEDING RATE ON BARRAMUNDI (Lates calcarifer) JUVENILE

Abstract

The present study examined how temperature and feeding rate interact to influence survival rate, growth performance, respiration, and feeding ability in juvenile Barramundi (Lates calcarifer). Twenty-day-old fish were cultured for 28 days under three temperatures (30, 32 or 34°C) combined with three feeding rates (50%, 75% or 100% of the recommended ration), followed by another 28 days of post-experimental recovery at 30°C with a full feeding rate (100%). During the experimental stage, the survival rate varied between 69.0% and 94.0%, reaching its maximum at 30°C with a full feeding rate (100%) and declining to the lowest value at 34°C under the 50% feeding rate. Growth performance was significantly affected by the combined effects of temperature and feeding rate (P < 0.0001). The greatest final length (1.50 ± 0.12 cm) and weight (0.05 ± 0.012 g) occurred at 30°C and 100% feeding, corresponding to SGR_L = 2.10 ± 0.26% day⁻¹ and SGR_W = 5.72 ± 0.80% day⁻¹, whereas the lowest growth (0.88 ± 0.04 cm; 0.01 ± 0.001 g) was recorded at 34°C and 50% feeding. Respiratory activity increased with temperature: gill cover movements rose from 142.00 ± 6.26 times min⁻¹ (30°C) to 162.78 ± 3.41 times min⁻¹ (34°C), while oxygen consumption ranged between 0.08 ± 0.01 and 0.81 ± 0.14 ppm 5 min⁻¹. Feeding ability varied slightly among treatments (12.5 - 18.3 Artemia 5 min⁻¹). During the 28-day recovery stage, survival reached 100% in all treatments, and fish previously exposed to 34°C exhibited significant compensatory growth, attaining 2.67 ± 0.07 cm and 0.25 ± 0.037 g at 100% feeding. These findings indicate that optimal growth and physiological efficiency of L. calcarifer juveniles occur at 30°C with full ration, while elevated temperature and feed restriction impair growth and metabolism but do not compromise recovery potential.