Feeding and locomotion are not only the primary physiological activities but also the main energy consumption processes in fishes.Studies related to feeding metabolism have demonstrated that the main energy expenditure in feeding is caused by assimilatory process of dietary nutrients.The energy expenditure of protein assimilation is much lower than that in terraneous vertebrate.Imbalance of dietary nutrients will increase the energy expenditure during the process of assimilation; there is trade-off between energy expending in activity of feeding and locomotion vs.maintenance in fish.The trade-off is limited by the maximum potential metabolism ability.Inter-specific differences are found in feeding and locomotion metabolism,other characteristic,as well as in competition mode.The investigation on the relationship between metabolism characteristic of feeding and locomotion with the ecological habits of fish can be taken as one important research topic in fish energetics in the further studies.