Nowadays, lower post-release survivorship of hatchery-reared fish in natural aquatic bodies has attained great attention and research is in progress to determine the reasons for their higher mortality. It is assumed that hatchery rearing environments negatively affect the physiological stress response of the fish. Thus, understanding how rearing environments modulate this is important for the well-being of fish. Here, an attempt has been made to assess the influence of two early rearing environments, i.e., barren (BR), mimic the conventional hatchery rearing environment; without any substrate and enrichment items and structurally enriched (ER), containing multi-colored gravel substrate, cobbles and plants, on the stress regulators i.e., HPI-axis and brain monoaminergic system of fish. Three-day old grass carp (Ctenopharyngodon idella) postlarvae were reared up to the fingerling stage in the aforementioned environments. For the stress assay, fish were subjected to net capture followed by 30 min confinement in a small container at a lower water level. The pre- and post-stress responses were compared by evaluating their water-borne cortisol and the mRNA level of corticotropin releasing hormone (CRH), dopamine D1A receptor (DRD1A) and hydroxytryptamine receptor 2B (HTR2B) in the whole brain through qPCR analysis. Results of two-way ANOVA revealed significantly low (p < .001) post-stress concentration and release rate of water-borne cortisol and pre- and post-stress expression of CRH, DRD1A and HTR2B genes in the ER than BR fish. It is concluded that a structurally complex early rearing environment reduces the stress level in fish.

如今，孵化场饲养的鱼在自然水生生物中释放后的较低存活率已引起广泛关注，并且正在进行研究以确定其较高死亡率的原因。假定孵化场的饲养环境会对鱼类的生理应激反应产生负面影响。因此，了解饲养环境如何调节这对鱼类的健康很重要。在这里，已经尝试评估两个早期饲养环境的影响，即贫瘠（BR）模仿传统的孵化场饲养环境；在压力调节剂（即鱼的HPI轴和脑单胺系统）上没有任何底物和富集物，并且没有结构丰富的（ER），其中包含多色的砾石底物，卵石和植物。三天大的草鱼（在上述环境中，将尾鳍小夜蛾（Ctenopharyngodon idella）幼虫饲养到鱼种阶段。为了进行压力测定，将鱼进行净捕获，然后在较低水位的小容器中封闭30分钟。通过qPCR分析评估整个大脑中的水皮质醇和促肾上腺皮质激素释放激素（CRH），多巴胺D1A受体（DRD1A）和羟色胺受体2B（HTR2B）的mRNA水平，从而比较了应激前后的反应。双向方差分析的结果表明，与BR鱼相比，ER中ER的CRH，DRD1A和HTR2B基因在应激后的浓度和释放率显着较低（p <.001），并且水溶皮质醇的释放速率和应激前后的表达也很低。结论是，结构复杂的早期饲养环境降低了鱼类的压力水平。