The effectiveness of two different hormonal treatments or a saline control on sperm characteristics, plasma sex steroids and testes histology of male Longspine scraper, Capoeta trutta (Heckel, 1843) collected from the wild and maintained in captivitywere tested. Fish injectedwith Ovaprim™had significantly increased gonadosomatic index (GSI) and sperm volume, but had decreased spermatozoa concentration and spermatocrit compared with control. Fish injected with hCG had significantly decreased motility duration of their sperm, as well as decreased spermatozoa concentration and spermatocrit. Both treatments increased seminal plasma pH compared with control, while decreases in osmolality of seminal plasma occurred only in Ovaprim™-treated fish. Hormonal treatments altered the seminal plasma sodium (Na+), calcium (Ca2+), magnesium (Mg2+), glucose, phosphorus, urea, creatinine, alanine aminotransferase (ALT), and alkaline phosphatase (ALP) concentrations. However, neither treatment affected the seminal plasma potassium (K+), chloride (Cl−), uric acid, total protein, cholesterol, triglycerides, and aspartate aminotransferase (AST) concentrations. The concentration of 17,20β-dihydroxy-4-pregnen-3-one (DHP) in the plasma was significantly enhanced by Ovaprim™ treatment, but not by hCG. On the other hand, plasma testosterone (T) was significantly elevated by both treatments. Histological examination of the testes revealed stimulation of testicular maturation following treatment with Ovaprim™,with lobules observed that were filled exclusivelywith a large number of spermatozoa (spz). In summary, hormonal treatments stimulated steroidogenesis and spermiation in male C. trutta, with highest efficiency of the Ovaprim™ treatment. Therefore, it can be concluded that like many other cyprinids, dopamine inhibitory action was operating in C. trutta, thus requiring anti-dopaminergic and hormonal treatments to overcome this in order to maximize steroidogenesis and induction of spermiation
