The present study was conducted to investigate the impact of G.catenatum on the feeding behavior of P.viridis. An experimental group fed with G.catenatum and a control group fed with Skeletonema costatum were established. Short-term (1 hour) and long-term (38 days) clearance rate experiments were carried out. The results showed that the clearance rate of P.viridis, whether feeding on toxic or non-toxic algae, as the densty of algae cells increased, initially increased and then decreased, reaching the peak when the algal cell density approached the threshold density for red tide. The highest clearance rates observed in the experimental and control groups were (3.04±0.02) and (3.70±0.03) L/(g·h), respectively. Compared to the control group, the clearance rate of P.viridis in the experimental group exhibited a significant decrease (P<0.05), indicating that G.catenatum had an influence on the feeding behavior of P.viridis. Furthermore, the long-term filtration did not cause significant changes in the clearance rate, which remained relatively stable at the initial level.