Testicular Morphology and Histology, Sperm-Releasing Pattern, and Size at First Maturation of Congaturi Halfbeak Hyporhamphus limbatus (Hemiramphidae) in Southwest Vietnam

The present study investigated various reproductive aspects of male Hyporhamphus limbatus to address this knowledge gap. Four hundred sixty-three specimens were collected monthly from the aforementioned provinces between October 2023 and September 2024. Macroscopic examination indicated four distinct testicular developmental stages characterized by variations in shape and color. Histological analysis of mature testes demonstrated the presence of multiple spermatogenic stages at stage IV (spermatogonia, spermatocytes, spermatids, and spermatozoa), indicating a potential multi-batch spawning strategy. The highest gonadosomatic index values were recorded in September and October, suggesting the peak active reproductive period. Males reached first sexual maturity at a fork length of 11.28 cm. These findings provide critical insights into the reproductive biology of H. limbatus in the Vietnamese coastal region, contributing valuable data for developing sustainable exploitation and conservation strategies for this ecologically and economically important species.