Several infective fungal pathogens as well as T-2 mycotoxin proved to exert drastic effects on fish fecundity.Icthyophonus showed white nodules with multinucleated spherical bodies (resting spores) in testes of males Oreochromis niloticus with moderate drop in sperm density. Among females Icthyophonus showed macro and microscopic white nodules in ovarian tissue of Oreochromis niloticus while in Cyprinus carpio showed only microscopic lesions. Absolute fecundity, hepatosomatic, gonadosomatic indices and total protein showed highly significant drop among Oreochromis niloticus and Cyprinus carpio infected with Icthyophonus.Fusarium infection in Clarias gariepinus revealed clinical signs appeared as 100 % and 70 % among both females and males respectively. Relative and absolute fecundity as well as total protein and liver enzymes levels showed highly significant drop among both sexes. Treatment with garlic and black seed promoted growth and relative fecundity but failed to perform complete remedy of absolute fecundity.T-2 toxin in Oreochromis niloticus showed highly significant drop in relative and absolute fecundity as well as total protein. Ginger treatment appeared effective only with males where it significantly improved the sperm density as well as its live %.