Tripathy, PS; Parhi, J; Mandal, SC; ,
Steroid hormones are associated with the regulation of various processes in fish, like embryonic development, sex differentiation, metabolism, immune responses, circadian rhythms, stress response, and reproduction. Steroids in fish are generally classified into C21, C19, and C18 steroids based on their structure. These steroids like estrogens and androgens are used in fish farming to increase fish production based on sexual dimorphism. Progesterone (P4), 17,20β-dihydroxy-4-pregnen-3-one (17,20βP or MIH or DHP), 17,20β,21-trihydroxy-4-pregnen-3-one (20βS) and 11-deoxycortisol (S) are some of the major C21 steroids that are essential for gonadal maturation and production of other endogenous steroids. The C19 steroids, i.e. testosterone (T), 17α-Methyltestosterone (MT), and 11-Ketotestosterone (11-KT) classified as androgens help in fish spermatogenesis and C18 steroids, called as Estranes, are known as female hormones. Except for the role of steroids in fish reproduction they have a major role in immunity, puberty, and stress. Corticosteroids, a major C21 steroid, are associated with stress response in fish. Steroids like, 17β-estradiol (E2), 11KT, medroxyprogesterone, 17α,20β-dihydroxy-4-pregnen-3-one (DHP), are associated with fish adaptive and innate immunity response. Similarly, 11KT is a major steroid for fish puberty. At present, further insights are required in the field of synthetic steroids in fish and their impacts over various roles in fish physiology and future economic importance.