Background. Ultraviolet (UV-B) radiation affects the immune system of fish. Dietary supplementation of natural immunostimulants may enhance the immunity of fish. The presently reported investigation evaluates the UV-B protective property of Achyranthes aspera seed in larvae of rohu, Labeo rohita (Hamilton, 1822). Materials and methods. Larvae (1.19 ± 0.03 g) were fed four formulas of diet containing 0.0% (control), 0.1%, 0.5%, and 1.0% Achyranthes aspera seeds. After 51 days, larvae of each feeding treatment were divided into two groups. One groups was exposed to UV-B radiation (80 µW · cm–2) and the other one remained unexposed. Results. Average weight of fish was significantly (P < 0.05) higher in fish fed 0.5%-seed-supplemented diet (compared to other treatments). UV-B radiation affected the growth of fish fed 0.1%-seed-supplemented- and control diets; other two treatments remained unaffected. Total serum protein-, albumin-, and globulin levels were significantly (P < 0.05) higher in exposed fish compared to the unexposed ones. Among the exposed groups, serum glutamic oxaloacetic transaminase and serum glutamate pyruvate transaminase levels were minimum in fish fed 1.0%-seed-supplemented diet, whereas the highest levels of myeloperoxidase, hemagglutination titre, and white blood cells were found in fish fed 0.5%-seed-supplemented diet group. Conclusion. Dietary supplementation of A. aspera seed at 0.5% level enhanced the growth and immunity of UV-B exposed fish.

Rohu, UV-B radiation, Achyranthes aspera seed, immunostimulation