Effects of dietary garlic supplementation on growth, survival, and hematological parameters of juvenile <i>Clarias macrocephalus</i> under low salinity

This study evaluated the dose-dependent effects of dietary garlic ( Allium sativum ) supplementation on growth performance, survival, and hematological parameters of juvenile bighead catfish ( Clarias macrocephalus ) reared under low-salinity (2‰) conditions. A 60-day feeding trial was conducted using four experimental diets containing 0, 10, 20, and 30 g kg⁻¹ garlic powder in a completely randomized design with triplicate groups. Fish fed 20 g kg⁻¹ garlic exhibited growth performance (final mean weight, weight gain, daily weight gain, and specific growth rate in weight) comparable to the control and significantly higher than that of fish fed 10 g kg⁻¹ (P ≤ 0.05). In contrast, the 30 g kg⁻¹ treatment showed intermediate values. Survival was highest at 20 g kg⁻¹ and significantly reduced at 30 g kg⁻¹ (P ≤ 0.05). Feed conversion ratio, and most monitored hematological parameters were not significantly affected by dietary treatments (P ≥ 0.05), although leukocyte count was significantly higher at 20 g kg⁻¹ compared to 30 g kg⁻¹ (P ≤ 0.05). These findings indicate a dose-dependent response to garlic supplementation, with 20 g kg⁻¹ representing an appropriate inclusion level under the present conditions. The results provide practical implications for the use of garlic as a functional feed additive in aquaculture systems affected by salinity intrusion. Further studies incorporating functional and mechanistic analyses are recommended to clarify the underlying biological processes.