The mixotrophic microplankton, combination of phototrophic and heterotrophic, are capable of survive when exposed under variable complex marine environment, becoming the dominant species in most of the marine ecosystem. The rate of carbon fixation and contribution of carbon sink by those mixotrophic microplankton varied with the biodiversity spatially and temporally. However, current carbon evaluation models of marine ecosystem are mainly focused on the phototrophic microplankton. The role of mixotrophic or heterotrophic characteristics is ignored. Therefore, a series studies had conducted on Type IV mixotrophic Mesodinium and Dinophysis, to understand their nutritional strategy driven by the photosynthesis and predation during the manipulated laboratory experiments. ‘Dinophysis-Mesodinium-cryptophyte’ were the known food chain in planktonic ecosystem. Seven levels of cryptophyte (Mesodinium: cryptophyte = 1:0, 2:1, 1:1, 1:2, 1:3 and 1:5) were supplied as prey, showing that Mesodinium would have the best carbon fixation when prey concentration as low as 1000 cells/mL (ratio of 2:1). The Mesodinium were then naturalized by different qualities (NP ratio and types) of cryptophyte, getting four NP ratio of Mesodinium (18, 12, 8 and 5). The four different qualities of Mesodinium were then supplied to Dinophysis for predation. The pathway or transformation of carbon are tracing in cellular, population and community levels, showing that Dinophysis are better fixing carbon when dissolved inorganic nitrogen is sufficient. At the end, the conceptual model, Perfect Beast plus (PB+), equipped with experimental data was established. This study provides an effective tool to better evaluate the carbon fixation in the microplankton ecosystem.