Abstract: To explore the consumption of energy sources and swimming performance of juvenile Gambusia affinis and Tanichthys albonubes after starvation, contents of glycogen, lipid and protein, burst swimming speeds (U_burst), and critical swimming speeds (U_crit) at different starvation times (0, 10, 20， 30 and 40 days) were evaluated. The results showed that, at 0 day, contents of glycogen and lipid were significantly lower in G. affinis than those in T. albonubes, whereas no significant difference in content of protein between two experimental fish was found. Swimming speeds in G. affinis were significantly lower than those in T. albonubes for all swimming performances. After different starvation scenarios, content of glycogen both in G. affinis and T. albonubes decreased significantly in power function trend with starvation time and were close to zero after starvation for 10 days, whereas the contents of lipid and protein were linearly significantly decreased. The slope of line regression equation between content of lipid and starvation time in G. affinis was significantly lower than that in T. albonubes, whereas there was a significantly higher slope of line equation between content of protein and starvation time in G. affinis. 40 days later, the consumption rate of glycogen both in G. affinis and T. albonubes were significantly higher than that of lipid, while the consumption rate of protein was the least. Consumption amounts of glycogen in all experimental fish were the least, G. affinis consumed more protein than lipid, and T. albonubes consumed more lipid than protein. U_burst and U_crit decreased significantly linearly with starvation time for all experimental fish. Slope of linear equation between U_burst and starvation time was not significantly different between G. affinis and T. albonubes. However, the straight slope between U_crit and starvation time was significantly lower in G. affinis than that in T. albonubes. These findings indicated that there was close relationship between the consumption of energy sources and swimming performance in starvation. Although the store amounts of energy sources and swimming performance were lower in G. affinis than those in T. albonubes, G. affinis mainly used protein during starvation. The result of more stable lipid content and U_crit in G. affinis in starvation  compared with that in T. albonubes indicated that G. affinis had a fair endurance to starvation, which helped them to adapt to the poor nutrition environment in stream habitat.