Effect of black cumin seed oil (Nigella sativa) and nettle extract (Quercetin) on enhancement of immunity in rainbow trout, Oncorhynchus mykiss (Walbaum)

► The study examined the effect of plant supplement on the immune response of fish. ► Treatment groups showed enhancement in the immune parameters compared to controls. ► Treatment groups showed higher significant differences in total serum IgM levels. ► The highest doses of both supplement showed the highest significant difference.