Improving Cold Tolerance in Labeo rohita: Effects of Job's Tears (Coix lacryma-jobi L.) as a Natural Feed Additive

This study investigated the effects of Job’s tears (Coix lacryma-jobi L.) as a feed additive on cold tolerance in Labeo rohita (initial weight: 15.2±0.3 g), marking the first evaluation of its health benefits in fish or aquaculture. Three doses (low: 0.5%, medium: 1%, and high: 2% of diet) were tested over an 8-week period, with fish fed to apparent satiation twice daily. Fish were subjected to a cold stress test (15°C), and physiological, biochemical, and molecular parameters were assessed. Blood samples were collected from the caudal vein of anesthetized fish at 0, 12, and 24 hours during the cold stress test. The medium dose (1%) showed the most significant improvements in cold tolerance, evidenced by enhanced survival rates, reduced plasma cortisol levels, and up regulation of cold-tolerant genes. These novel findings suggest that Job’s tears could be an effective feed additive for improving cold tolerance in L. rohita aquaculture, opening new avenues for natural stress mitigation in fish farming in subtropical and temperate regions.