Fish are the main source of long-chain polyunsaturated fatty acids (LC-PUFA, >C₁₈) for human consumption. In general, it has been widely observed that the fatty acid (FA) profiles of farmed fish are reflective of the diet. However, the degree of tissue FA “distortion” based on incorporation of different dietary FA into fish tissues varies greatly depending on FA type, fish species and environmental factors. In terms of fish FA composition, this variation has not been comprehensively reviewed, raising the question: “Are fish what they eat?”. To date, this remains unanswered in detail. To this end, the present review quantitatively summarized the ‘diet-fish’ FA relationship via an analysis of FA composition in diets and fish tissues from 290 articles published between 1998 and 2018. Comparison of this relationship among different fish species, tissue types or individual FA was summarized. Furthermore, the influence of environmental factors such as temperature and salinity, as well as of experimental conditions such as fish size and trophic level, feeding duration, and dietary lipid level on this relationship are discussed herein. Moreover, as a means of restoring LC-PUFA in fish, an emphasis was paid to the fish oil finishing strategy after long-term feeding with alternative lipid sources. It is envisaged that the present review will be beneficial in providing a more comprehensive understanding of the fundamental relationship between the FA composition in diets, and subsequently, in the farmed fish. Such information is integral to maintaining the quality of farmed fish fillets from the perspective of FA composition.

鱼是长链多不饱和脂肪酸（LC-PUFA，>C ₁₈) 供人类食用。一般而言，已广泛观察到养殖鱼类的脂肪酸 (FA) 分布反映了饮食。然而，基于将不同膳食 FA 掺入鱼类组织而导致的组织 FA“扭曲”程度因 FA 类型、鱼类种类和环境因素而异。在鱼类 FA 组成方面，这种变化尚未得到全面审查，引发了一个问题：“鱼吃的是什么？”。迄今为止，这个问题仍未得到详细解答。为此，本综述通过分析 1998 年至 2018 年间发表的 290 篇文章中饮食和鱼类组织中的 FA 组成，定量总结了“饮食-鱼类”FA 关系。比较不同鱼类、组织类型或个体之间的这种关系FA 进行了总结。此外，本文讨论了环境因素（例如温度和盐度）以及实验条件（例如鱼的大小和营养水平、摄食持续时间和膳食脂质水平）对这种关系的影响。此外，作为恢复鱼中 LC-PUFA 的一种手段，在长期饲喂替代脂质来源后，重点关注鱼油精加工策略。预计本综述将有助于更全面地了解膳食中 FA 组成以及随后养殖鱼类中 FA 组成之间的基本关系。从 FA 组成的角度来看，此类信息对于保持养殖鱼片的质量是不可或缺的。喂养持续时间和饮食脂质水平与这种关系在本文中进行了讨论。此外，作为恢复鱼中 LC-PUFA 的一种手段，在长期饲喂替代脂质来源后，重点关注鱼油精加工策略。预计本综述将有助于更全面地了解膳食中 FA 组成以及随后养殖鱼类中 FA 组成之间的基本关系。从 FA 组成的角度来看，此类信息对于保持养殖鱼片的质量是不可或缺的。喂养持续时间和饮食脂质水平与这种关系在本文中进行了讨论。此外，作为恢复鱼中 LC-PUFA 的一种手段，在长期饲喂替代脂质来源后，重点关注鱼油精加工策略。预计本综述将有助于更全面地了解膳食中 FA 组成以及随后养殖鱼类中 FA 组成之间的基本关系。从 FA 组成的角度来看，此类信息对于保持养殖鱼片的质量是不可或缺的。预计本综述将有助于更全面地了解膳食中 FA 组成以及随后养殖鱼类中 FA 组成之间的基本关系。从 FA 组成的角度来看，此类信息对于保持养殖鱼片的质量是不可或缺的。预计本综述将有助于更全面地了解膳食中 FA 组成以及随后养殖鱼类中 FA 组成之间的基本关系。从 FA 组成的角度来看，此类信息对于保持养殖鱼片的质量是不可或缺的。