Brief research report: Contrast-enhanced radiography for gonadal visualization in Nile tilapia

Evaluation of gonadal visualization is important for reproductive management in aquaculture. This study introduces a novel method using a positive contrast medium in digital radiography to enhance gonadal visualization in Nile tilapia (Oreochromis niloticus). The contrast medium was administered retrogradely via an intravenous catheter sheath before laterolateral and dorsoventral radiographic imaging. In well-developed males, the agent outlined the spermatic ducts and branching channels. In well-developed females, it highlighted the spaces between oocytes, appearing as rounded radiolucent granular structures within a radiopaque background. This method allows for the preliminary assessment of reproductive status, including gonadal development and potential fecundity. Positive contrast radiography enhances animal welfare and may support breeding efficiency, supporting its integration into aquaculture for sustainable reproductive management.