Heavy metals such as lead, copper and zinc had been found in mangroves, shrimp and milkfish at Blanakan fishponds area, Subang, West Java. However, information about the role of phytoplankton in accumulating heavy metals has not been studied yet. Phytoplankton that is known to live dominantly in contaminated waters is Nitzschia. This research aimed to identify relationship between copper (Cu) concentration in phytoplankton and Nitzschia dominance. Phytoplankton sampling was done 3 times during July until August 2016 at three ponds. Phytoplankton was identified using phytoplankton identification book and phytoplankton abundance were calculated based on sub sample method with sedgewick-rafter. Measurements of heavy metal concentration were conducted using Atomic Absorption Spectrophotometer. Results showed that Nitzschia dominance at three ponds were 1992, 477 and 322 plankton/10 L, respectively. Cu concentrations in phytoplankton at three ponds were 0.07, 0.02 and 0.02 ppm, respectively. There was a significant positive correlation between Cu content on phytoplankton and Nitzschia abundance in all stations, with correlation coefficient (r) = 0.7518. It can be stated that the more Cu content on phytoplankton, the more abundant of Nitzschia was.