The invasion of aquatic vascular plant has caused many complicated problems we should disentangle. The parrot feather, Myriophyllum aquaticum, now has a world-wide distribution and been one of invasive exotic plants in freshwater systems. Although many studies have been published, their effects on native fauna remain unclear. We investigated micro and macro fauna inhabiting beds of the parrot feather and two native plants in a natural pond on Okinawajima Island where the early stage of their invasion has been found. The species richness of macroinvertebrates (1mm <) which has been often targeted for studies about aquatic plant invasions was most rich in the bed of the parrot feather regardless of seasonal fluctuation, while their abundance varied seasonally among three species. The index of biodiversity (Simpson-Yule index) was also the highest in the parrot feather. However, abundance, species richness and the index of biodiversity of zooplanktons (40μ <) which has been rarely targeted for studies about aquatic plant invasions were all the lowest in the parrot feather regardless of seasonal fluctuation. The invasion of the parrot feather affected macroinvertebrates and zooplanktons differently. This situation should be considered in future studies.