The teleost zebrafish (Danio rerio), an established model for human skeletal diseases, is reared under controlled conditions with defined parameters for temperature and photoperiod. Studies aimed at defining the proper rearing density have been performed with regard to behavioural and physiological stress response, sex ratio and reproduction. Studies concerning the effect of rearing density on the skeletal phenotype are lacking. This study is designed to analyse the response of the skeleton to different rearing densities and provides a description of the skeletal deformities. Wild type zebrafish were reared up to 30 dpf (days post-fertilization) in a common environment. From 30 to 90 dpf, animals were reared at three different densities: high density (HD) 32 fish/L, medium density (MD) 8 fish/L and low density (LD) 2 fish/L. Animals at 30 and 90 dpf were collected and whole-mount stained with Alizarin red S to visualise mineralized tissues. The entire skeleton was analysed for meristic counts and 172 types of deformities. The results showed that rearing density significantly influenced the specimens' average standard length, which decreased with increasing rearing density. Differences concerning meristic counts among the three groups were not observed. Rearing density-independent malformations affected the ribs, neural arches and the spines of the abdominal region as well as vertebrae of the caudal complex. The HD group showed the highest number of deformities per specimens, the highest number of observed types of deformities and, together with the MD group, the highest frequency of specimens affected by severe deformities. In particular, the HD group showed deformities affecting arches, spines and vertebral centra in the caudal region of the vertebral column. This study provides evidence of an effect of rearing density on the development of different skeletal phenotypes. This article is protected by copyright. All rights reserved.

中文翻译：

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斑马鱼（Danio rerio）骨骼的可塑性和骨骼畸形与饲养密度有关

硬骨斑马鱼 (Danio rerio) 是一种已建立的人类骨骼疾病模型，在具有明确温度和光周期参数的受控条件下饲养。已经针对行为和生理应激反应、性别比例和繁殖进行了旨在确定适当饲养密度的研究。缺乏关于饲养密度对骨骼表型影响的研究。本研究旨在分析骨骼对不同饲养密度的反应，并提供骨骼畸形的描述。野生型斑马鱼在共同环境中饲养达 30 dpf（受精后天数）。从 30 到 90 dpf，以三种不同的密度饲养动物：高密度 (HD) 32 条鱼/L、中密度 (MD) 8 条鱼/L 和低密度 (LD) 2 条鱼/L。收集 30 和 90 dpf 的动物，并用茜素红 S 对其进行整体染色，以观察矿化组织。分析了整个骨骼的分生计数和 172 种畸形。结果表明，饲养密度显着影响标本的平均标准长度，随着饲养密度的增加而降低。未观察到三组之间关于分生计数的差异。与饲养密度无关的畸形影响肋骨、神经弓和腹部区域的脊椎以及尾椎复合体的椎骨。HD 组显示每个标本的畸形数量最多，观察到的畸形类型数量最多，与 MD 组一起，标本受严重畸形影响的频率最高。特别是，HD 组显示出影响脊柱尾部区域的弓、棘和椎体的畸形。本研究提供了饲养密度对不同骨骼表型发育影响的证据。本文受版权保护。版权所有。