Stable carbon and nitrogen isotope ratios (N) provide a predictable method to evaluate the contribution of food sources to bighead carp (δ¹⁵N of bighead carp in four treatments, such as fertilization (group A), fertilization + 1/2 feeding (group B), fertilization feeding (group C), and feeding (group D) to analyze variations in the stable isotope ratios and the contribution rates of different food sources. The results showed that the N values in group A tended to be higher than those in the other groups[(−23.8±0.1)‰ and (10.8±0.4)‰, respectively, <0.05]. Zooplankton, particulate organic matter, and artificial feed were the food sources used in the different treatments, and their N values were lower than those of bighead carp. Zooplankton was a major food source for bighead carp in group A, with a mean contribution rate of (65.6±3.2)%, whereas artificial feed was the main food source in the other three groups, of which the contribution rate in group B was relatively higher (82.1%). These results suggest that artificial feed was absorbed well by bighead carp. However, fertilizing the cultured plankton effectively improved the contribution by artificial feed, decreased the amount of feed, and reduced the pollution caused by residual feed. The present study provides a theoretical basis to invest and culture bighead carp.