Ariki, Daniel Guimarães Figueiredo [UNESP]Roza de Abreu, Mariana [UNESP]de Jesus Silva, Laíza Maria [UNESP]Sato, Rafael Tomoda [UNESP]Batlouni, Sergio Ricardo [UNESP]2023-07-292023-07-292023-07-01Animal Reproduction Science, v. 254.0378-4320http://hdl.handle.net/11449/248951In this study, we aimed to propose changes in the protocol of cultured Astyanax altiparanae hypophysation to increase the maximum ovulation rate of 60% registered previously. To that two consecutive experiments were conducted. In the first experiment, three carp pituitary homogenate (CPH) doses (3, 6, and 9 mg/kg) were administered in a single injection, while in the second experiment, the 6 mg/kg CPH dose was tested either in single or double injections. In the first experiment, a single injection of 3 mg/kg CPH did not induce final oocyte maturation or spawning, while a dose of 6 mg/kg CPH resulted in an increase in the plasma level of prostaglandin (PGF2α) at ovulation. The single higher dose of 9 mg/kg CPH did not improve reproductive performance and even though anticipated the resumption of meiosis it was detrimental to the spawning rate. In the second experiment, the dose of 6 mg/kg CPH fractionated into two injections led to a higher spawning rate, spawning volume per female body mass, frequency of post-ovulatory complexes, and PGF2α concentration at ovulation compared to the single injection. The most effective treatment remained the 6 mg/kg of CPH fractionated into two injections, but still providing very low proportion of ovulated females (∼40 %). Overall, this study indicates that the spawning protocols for this species need to be improved to induce ovulation in a larger number of females and be more potent in those females that respond positively.engHormonal inductionHyphophysationLambariPGF2αProstaglandinArtigo10.1016/j.anireprosci.2023.1072622-s2.0-85161286751