College of Aquaculture and Fisheries, Can Tho University, Can Tho, Vietnam.
J Fish Biol. 2023 Jun;102(6):1296-1310. doi: 10.1111/jfb.15378. Epub 2023 Mar 27.
Information on the reproductive biology of fish species is essential for fisheries management, conservation and culture potential assessment. Therefore, this study aimed to understand the sex-based morphological differences and reproductive characteristics of Cephalocassis borneensis, an ariid species with a rapid decline of wild populations. Fish samples were collected monthly from local fishermen (n = 1092) in the Vietnamese Mekong River over a year. Morphological analyses revealed that sexual dimorphism was observed in mature, but not immature, fish. The length at first maturity (L ) was smaller for males (11.5 cm) than for females (12.5 cm). Mature males had larger head length and pre-pectoral distance than mature females, increasing the space for oral incubation of fertilized eggs and larvae in males. Conversely, females were larger in three head parameters (head angle, head width and head depth) and three abdomen parameters (body deep, ventral fin length and distance between pectoral and ventral fin) involved in ovary development. Paternal mouth-brooding behaviour is an important reproductive strategy in C. borneensis to increase offspring survival. Monthly variations in gonado-somatic index and condition factor (K) and the presence of maturation stages indicated that C. borneensis spawns year-round, mainly in the rainy season from June to October. This species' fecundity was relatively low, from 10 to 31 eggs per female of quite large sizes (about 7.30 ± 0.68 mm in diameter). Besides, non-functional oocytes (hyaline eggs) of smaller size (<3 mm) were found in the females' ovaries. Low fecundity with large eggs and paternal care indicated that the species is an equilibrium strategist. These characteristics are critical in developing ariid species conservation plans, such as setting the time and mesh-size for fishing, and domestication programmes in artificial conditions.
鱼类生殖生物学信息对于渔业管理、保护和养殖潜力评估至关重要。因此，本研究旨在了解盔鱼（Cephalocassis borneensis）的性别形态差异和生殖特征，盔鱼是一种野生种群迅速减少的 Ariidae 物种。在一年的时间里，每月从越南湄公河的当地渔民（n=1092）那里收集鱼类样本。形态分析表明，性二型性仅在成熟鱼中观察到，而在不成熟鱼中则未观察到。初次成熟体长（L）雄性（11.5 厘米）小于雌性（12.5 厘米）。成熟雄性的头长和前胸距大于成熟雌性，为受精卵和幼鱼的口腔孵化提供了更大的空间。相反，雌性在三个头部参数（头角、头宽和头深）和三个腹部参数（体深、腹鳍长度和胸鳍与腹鳍之间的距离）上更大，这些参数与卵巢发育有关。雄性的口孵育行为是 C. borneensis 提高后代存活率的重要繁殖策略。性腺体指数和条件因子（K）的逐月变化以及成熟阶段的存在表明，C. borneensis 全年产卵，主要在雨季（6 月至 10 月）产卵。该物种的繁殖力相对较低，每个雌性约有 10 到 31 个卵，卵的大小相当大（直径约为 7.30±0.68 毫米）。此外，在雌性的卵巢中还发现了较小尺寸（<3 毫米）的无功能卵（透明卵）。低繁殖力与大卵和雄性亲代照顾表明该物种是一种平衡策略者。这些特征对于制定 Ariidae 物种保护计划至关重要，例如设定捕鱼时间和网目大小，以及在人工条件下的驯化计划。
