Improving the immune system in fish as an effort to prevent fish from disease attacks caused by pathogenic organisms, because disease attacks on fish are projected to continue to grow and cause mass death of cultured fish. Giving immunostimulants as additives to feed can be a strategy to improve the fish's immune system. Immunostimulants are compounds that are able to increase the non-specific immune response or the innate immune response. Nigella sativa L known as "Black Cumin" or Black Seed is one of the natural ingredients that can be used as medicine, including as an immunostimulant to increase the immune system which can prevent disease attacks. The part of the black cumin plant that is efficacious as a medicine for its seeds. The active compounds contained in N. sativa seeds are Thymoquinone, Dithymoquinone, Thymohydriquinone, and Thymol. Nigella sativa can increase the number of white blood cells, such as neutrophils, lymphocytes, and monocytes as an indicator of an increase in the immune system of fish. Several studies have shown that N. sativa can be used in the field of fisheries, especially to increase the body's resistance to disease. So the purpose of this article is to explain N. sativa as an immunostimulant in cultured fish that can increase the fish's body resistance to disease attacks. Based on the above studies, N. sativa L. seeds in powder or oil form can significantly increase the immune response, reduce mortality and increase the survival rate of fish infected with pathogenic organisms. Therefore, N. sativa L. seeds have the potential to be used as a dietary supplement immunostimulant to help increase the body's resistance to various types of cultured fish against diseasecausing pathogenic organisms. The dose given must be adjusted to the type of fish and the disease.