中文摘要：

2012年6月于重庆市北碚区歇马养殖场采集鲫鱼（Carassiusauratus）31尾，体质量（W）范围3.0～284.8g，体长（L）范围5.5～22.6cm，分为4个体长组，测定了鱼体化学组成，估算了能量密度。结果表明，鲫鱼含水量（WAT）、蛋白质含量（PRO）、脂肪含量（FAT）和灰分含量（ASH）占鱼体鲜重的百分比范围分别为68.58%～78.99%、7.81%～18.87%、0.55%～9.11%和3.25%～6.59%，能量密度（E）范围为2.06～7.68kJ·g-1。体质量与脂肪含量和能量密度的关系可分别描述为方程：FAT=0.0256W＋1.59（R2=0.561，n=31，p〈0.01）和E=0.0102W＋3.94（R2=0.395，n=31，p〈0.01）；含水量与脂肪含量和能量密度的关系可分别描述为方程：FAT=-0.855WAT＋67.5（R2=0.753，n=31，p〈0.01）和E=-0.380WAT＋33.1（R2=0.662，n=31，p〈0.01）。研究提示可以用体质量和含水量估测鲫鱼的脂肪含量和能量密度；随着个体体质量的增加，水分和脂肪之间存在近等比例的替代。

英文摘要：

31 specimens of Carassiusauratus were collected from Xiema fishery farms, Beibei, Chongqing in June, 2013. Body mass （W） ranged 3.0-284.8 g and body length （L） ranged 5.5-22.6 cm. The fish were divided into 4 groups based on their body length. Chemical compositions were measured and energy density was estimated. The results showed that the contents of water （WAT）, protein （PRO）, lipid （FAT） and ash （ASH）, ranged 68.58%- 78.99%, 7.81%- 18.87%, 0.55% -9.11% and 3.25%-6.59%, respectively. The energy density （E） ranged 2.06-7.68 kJ .g-1. The relationship between FAT or E and W could be described as; FAT=0. 025 6W＋1. 59 （R2 =0. 561, n=31, p〈0.01） and E=0. 010 2W＋3.94 （R2 =0. 395, n=31, p〈 0.01）. The relationship between FAT or E and W could be described as： FAT= -0. 855WAT＋67.5 （R2 =0. 753, n=31, p% 0.01） and E=-0. 380WAT＋33.1 （R2 =0. 662, n=31, p〈0.01）. The results suggest that lipid content and energy density of Carassius auratus can be estimated by body mass and water content. WAT is replaced with FAT approximately isometrically as the body mass increases.