Journal Article

Unraveling Growth Variation in Japanese Eel ( Anguilla japonica ): Integration of Feeding Behavior, Metabolic Phenotype, and Appetite Gene Profile

Li, Kang, Zeng, Xiangbiao, Xie, Bin, Liu, Tianyu, Jiang, Kanghong, Liu, Zhizhi, Liu, Liping, Liu, Jingwei, Wei, Zhenzhu, Jiang, Tianwei, Liu, Yanhe

2025

Overview

Significant growth heterogeneity is prevalent in farmed Japanese eels ( Anguilla japonica ), whereas its underlying causes remain poorly understood. The study investigated the metabolic, digestive, and behavioral phenotypic differences between fast‐ and slow‐growing A. japonica . A total of 100 elvers (22.88 ± 1.11 g) were randomly allocated into four net cages (25 individuals per cage). After 8 weeks of rearing, the three heaviest and three lightest individuals from each cage were selected and designated as fast‐growing eel (FGE) and slow‐growing eel (SGE), respectively. Plasma metabolic profiling revealed that SGE showed significantly lower levels of total cholesterol (TC), low‐density lipoprotein cholesterol (LDL‐C) and lactate compared to FGE, while aspartate aminotransferase (AST) was higher ( p < 0.05). Moreover, oxygen consumption rate (OR) and ammonia excretion rate (AR) in SGE were significantly higher than FGE. Significant differences in digestive and metabolic enzyme activities were observed, with SGE displaying lower amylase, trypsin, Na + ‐K + ‐ATPase, and ATPase levels than FGE ( p < 0.05). In behavioral phenotypes, SGE exhibited a longer latency time, along with reduced total feed intake and amount of feces than FGE, while no significant differences in relative feed intake or relative amount of feces. Additionally, compared to FGE, the expression levels of neuropeptide Y ( npy ) and ghrelin were significantly downregulated in SGE, whereas corticotropin‐releasing hormone ( crh ) mRNA upregulated ( p < 0.05). Multivariate analysis identified that AST and crh may serve as primary discriminators for SGE classification. In conclusion, the differences in feeding behavior, metabolic level, and digestive capacity were related to growth disparity between individual eels. These findings advanced our mechanistic understanding of growth variation in A. japonica and provided valuable insights for promoting uniform growth.

• Publisher: John Wiley & Sons, Inc
• Subject: ACTH / Adenosine triphosphatase / Ammonia / Anguilla japonica / Appetite / Aquaculture / Aspartate aminotransferase / Cages / Cameras / Catadromous species / Cholesterol / Comparative analysis / Corticotropin releasing hormone / Eels / Enzymatic activity / Enzyme activity / Excretion / Faeces / Feces / Feeding behavior / Feeding habits / Fish / Fisheries / Food / Foraging behavior / Genes / Ghrelin / Growth / Heterogeneity / Hormones / Lactate / Latency / Lipoproteins / Low density lipoprotein / Low density lipoproteins / Marine fishes / Metabolism / mRNA / Multivariate analysis / Na+/K+-exchanging ATPase / Neuropeptide Y / Oxygen consumption / Phenotypes / Physiology / Trypsin