The impact of adding aloin to water on the stress resistance of goldfish under transportation stress.

Transportation stress response can reduce the antioxidant and immune capabilities of fish. To develop a green and safe natural anti-stress agent, this study focused on goldfish (Carassius auratus) to investigate the alleviating effects and mechanisms of aloin against transportation stress. The effects of aloin (0, 50, 200 mg/L) on stress, antioxidant, and immune indicators under simulated transportation for 6 and 24 h were determined, and the expression of antioxidant, inflammatory, and complement-related genes was measured by qPCR. The results showed that transportation increased the serum glucose level, elevated tissue antioxidant enzyme activity, enhanced oxidative damage, and decreased tissue immune enzyme activity in goldfish. Aloin reduced stress response indicators, enhanced antioxidant activity and immune function, and reduced the total number of bacteria in the water body, with 200 mg/L being optimal. qPCR revealed that aloin improved goldfish's ability to cope with transportation stress by regulating the Nrf2-Keap1 antioxidant pathway in a tissue-specific manner, restoring the balance of pro-inflammatory and anti-inflammatory factors, activating the lectin complement pathway, and synergistically alleviating transportation stress in goldfish. In summary, aloin can alleviate transportation stress in goldfish, providing a practical basis for developing green anti-stress agents.