The tripletail Lobotes surinamensis inhabits tropical and subtropical oceans, including the South Atlantic, where information about its reproductive biology is scarce. We combined physiological and morphological tools to study the reproductive cycle of L. surinamensis in the western South Atlantic. Adult females and males were sampled in Paraty Bay (Rio de Janeiro, southeastern Brazil) for 2 years, and the animals were grouped into three seasons: spring, summer, and autumn/winter. Gonadal morphology, plasma levels of gonadal steroids, 17β-estradiol (E₂), 11-ketotestosterone (11-KT), and 17α-hydroxyprogesterone (17α-OHP) were quantified in females, and testosterone (T) and 11-KT were quantified in males. The gene expression of the β subunit of pituitary gonadotropins, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were evaluated in all seasons. The histological analysis of the gonads showed that L. surinamensis is a multiple spawner with an asynchronous oocyte development. The gene expression of fshβ did not change throughout the reproductive cycle in males and females, while the gene expression of lhβ in males was higher in the summer compared to the autumn/winter periods. Plasma E₂ was higher in females and 11-KT in males during spring. Gonadal development, plasma level of E₂ (females), and 11-KT (males) are indicators that L. surinamensis reproduce during the spring and summer in Paraty Bay, while the gene expression levels of gonadotropins in females and fshβ in males were not useful physiological tools to establish the reproductive season. The results suggest an active expression throughout the year, a profile expected in multiple spawning species, as proposed here for the L. surinamensis.

三尾Lobotes surinamensis栖息在热带和亚热带海洋，包括南大西洋，那里关于其生殖生物学的信息很少。我们结合生理学和形态学工具来研究南大西洋西部苏里南 L. surinamensis的生殖周期。成年雌性和雄性在帕拉蒂湾（巴西东南部里约热内卢）采样2年，将动物分为三个季节：春季、夏季和秋季/冬季。性腺形态、性腺类固醇的血浆水平、17β-雌二醇 (E ₂)、11-酮睾酮 (11-KT) 和 17α-羟基孕酮 (17α-OHP) 在女性中被量化，而睾酮 (T) 和 11-KT 在男性中被量化。在所有季节评估垂体促性腺激素β亚基、促黄体激素(LH)和促卵泡激素(FSH)的基因表达。性腺的组织学分析表明，L. surinamensis是一种卵母细胞发育不同步的多产卵动物。雄性和雌性在整个生殖周期中fshβ的基因表达量没有变化，而雄性中lhβ的基因表达量在夏季高于秋冬季。等离子 E ₂春季女性较高，男性 11-KT。性腺发育、血浆E ₂（雌性）和11-KT（雄性）是苏里南L. surinamensis在Paraty Bay春夏季繁殖的指标，而雌性促性腺激素和雄性fshβ的基因表达水平则没有建立生殖季节的有用生理工具。结果表明全年都有活跃的表达，这是在多个产卵物种中预期的特征，正如这里对苏里南乳杆菌所提出的那样。