Weaning of fish is a critical stage during larval rearing and could cause high mortality. Therefore, proper larval weaning period selection is crucial for the success of larviculture. This study aimed to find the effect of weaning on growth performance, histopathological features, and mortality rates in larvae of Sterlet Acipenser ruthenus. The experimental rearing was conducted from 7 to 38 d posthatch (dph) at a mean temperature of 18°C in a recirculating system. The experiment was carried out in three groups (each with three replicates) and placed in nine tanks (22 L) at a density of 10 individuals/L. The diet groups were made up of group C in which larvae were fed with nauplii of brine shrimp Artemia spp., group F7 in which larvae were weaned to dry feed 15 dph, and group F that was fed with dry feed throughout the experimental trial. During 15–38 dph, total wet body weight and total length were lowest in the group fed with formulated feed. Survival rate of larvae in group F7 was 90.45% and 70.05% during 7–14 and 15–22 dph, respectively. On the other hand, the survival rate of larvae fed only Artemia nauplii (group C) or formulated feed (group F) was 86.14% and 70.45% during 7–14 dph and 84.55% and 78.41% during 15–22 dph, respectively. The maximum height of the enterocytic epithelium was found in the individuals in group F7 (mean ± SD = 33.80 ± 2.56 μm). The average height of enterocytes of group F7 (n = 30 fish) larvae were significantly increased at 15, 23, and 38 dph compared with the larvae fed with formulated feed and live feed, but no significant changes were observed in the liver cells, including in the diameter of hepatocytes and their nuclei. This study provides evidence that Sterlet larvae should be fed with Artemia nauplii at 7–15 dph because fish gain a higher wet body weight and total length and develop a better liver and digestive tract.

中文翻译：

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早期断奶对幼小St鱼cip鱼的存活，生长和组织病理学的影响

断奶是幼体饲养的关键阶段，可能导致高死亡率。因此，适当的幼虫断奶期选择对于幼虫养殖的成功至关重要。本研究旨在发现断奶生长性能，组织病理学特征，并在小体鲟的幼虫死亡率的影响鲟。在循环系统中，在孵化后7到38天（dph）进行实验饲养，平均温度为18°C。实验分为三组（每组三个重复），并以10个人/升的密度放置在九个水箱（22升）中。饮食组由C组组成，在C组中，幼虫喂食无节幼体的盐水虾卤虫spp。，F7组，其中幼虫断奶至干饲料15 dph，F组在整个实验过程中均饲喂干饲料。在15-38 dph期间，饲喂配方饲料的组的总湿体重和总长度最低。F7组幼虫的存活率在7-14 dph和15-22 dph期间分别为90.45％和70.05％。在另一方面，幼虫的存活率只喂卤虫无节幼体（C组）或配合饲料（F组）为86.14％，并在分别在15-22 DPH 7-14 DPH和84.55％和78.41％，70.45％。在F7组的个体中发现了肠上皮的最大高度（平均值±SD = 33.80±2.56μm）。F7组肠上皮细胞的平均身高（n  = 与用配方饲料和活饲料喂养的幼虫相比，30 d幼虫在15、23和38 dph时显着增加，但是在肝细胞中未观察到显着变化，包括肝细胞及其核的直径。这项研究提供的证据表明，小体鲟幼虫应喂卤虫无节幼体在7-15 dph的，因为鱼获得更高湿重和总长度和开发出更好的肝脏和消化道。