Excessive dietary histamine inhibits growth performance and impairs intestinal and hepatic health in juvenile American eel (

Introduction: Histamine commonly accumulates in animal-derived feed ingredients and is detrimental to aquaculture species, but the adverse consequences of dietary histamine remain inadequately characterized. Here, we explored the physiological influences of different dietary histamine levels on the growth performance, as well as the intestinal and hepatic health, of American eels, a fish species intolerant to histamine. Methods: Five diets were prepared with total histamine levels of 48.94, 198.19, 355.31, 492.44, and 641.37 mg kg Results: American eels receiving diets with histamine levels exceeding 355.31 mg kg⁻¹ exhibited reduced growth performance, feed utilization, immune competence, intestinal mucosal and hepatocellular integrity, intestinal and hepatic antioxidant capacity, and intestinal digestive enzymes activities, along with elevated intestinal and hepatic malondialdehyde contents, compared to those fed the diet containing 48.94 mg kg Conclusion: These findings provide crucial insights regarding dietary histamine levels and underscore the importance of restricting histamine content in American eel diets.