Interspecific hybridization has been considered as a possible approach to improve biological traits and has been applied in aquaculture practices. In the present study, artificial hybridization was carried out in the small yellow croaker (SYC; Larimichthys polyactis) ♀ × large yellow croaker (LYC; L. crocea) ♂ by artificial insemination, and the processes of sex differentiation and gonadal development in SYC and its hybrid were investigated under controlled conditions. Histological analysis of SYC larvae showed that migrating primordial germ cells (PGCs) were observed at 4 days post-hatching (dph), a genital ridge was formed on the dorsal side of the peritoneum at 6 dph, and a pair of primary gonads was first observed at 10 dph. Signs of the differentiated ovary and ovarian cavity were observed at 45 dph. However, some presumptive testes showed alterations in morphology, including an increase in the number of oocytes and an enhanced basophilia at 50 dph. These presumptive testes seemed to alter again, and numerous gonial cells were arranged in cyst-like groups with several degenerating oocytes that developed into residual body-like structures during 60–90 dph. Compared with SYC, the hybrid had a lower number of PGCs and showed retarded gonadal development at the early stage. Ovarian differentiation in the hybrid was observed at 50 dph, while testicular differentiation occurred at 60 dph. The presence of vitellogenic oocytes and spermatozoa at 360 dph in the hybrids suggested that hybrid individuals can undergo successful gametogenesis in females and males, respectively. Overall, the present results suggest that morphological sex differentiation occurred at 40 and 50 dph in SYC and its hybrid, respectively, both of which have normal gametogenesis. Moreover, some level of heterosis (hybrid vigor) occurred in the growth of the hybrid (total length and body weight) compared with that in the growth of SCY over time. Gonadal development of the hybrid was also found to be advanced at 360 dph. The present information will contribute to the potential use and management of these fish for aquaculture.

种间杂交被认为是改善生物性状的一种可能方法，并已应用于水产养殖实践。本研究对小黄鱼（SYC; Larimichthys polyactis）♀×大黄鱼（LYC; L. crocea ）进行人工杂交。) ♂ 通过人工授精，在受控条件下研究了SYC及其杂种的性别分化和性腺发育过程。SYC幼虫的组织学分析表明，在孵化后4天（dph）观察到迁移的原始生殖细胞（PGCs），在第6天在腹膜背侧形成生殖嵴，并首先形成一对初级性腺。以 10 dph 观察。在 45 dph 观察到分化的卵巢和卵巢腔的迹象。然而，一些推定的睾丸显示出形态学改变，包括卵母细胞数量增加和 50 dph 时嗜碱性粒细胞增多。这些假定的睾丸似乎又发生了变化，许多生殖细胞排列成囊状组，有几个退化的卵母细胞在 60-90 dph 期间发育成残留的体状结构。与SYC相比，杂种的PGC数量较少，早期性腺发育迟缓。杂种中的卵巢分化在 50 dph 时观察到，而睾丸分化在 60 dph 时发生。杂种中 360 dph 的卵黄卵母细胞和精子的存在表明杂种个体可以分别在雌性和雄性中经历成功的配子发生。总体而言，目前的结果表明，SYC 及其杂种的形态性别分化分别发生在 40 和 50 dph，两者都具有正常的配子发生。而且，随着时间的推移，与 SCY 的生长相比，杂种的生长（总长度和体重）发生了某种程度的杂种优势（杂种优势）。还发现杂种的性腺发育以 360 dph 的速度进行。目前的信息将有助于这些鱼在水产养殖中的潜在利用和管理。