The authors investigated the influence of the garlic Nitellopsis obtusa on the occurrence of aquatic fungus species in the water of eutrophic lake, Blizno. More fungi were found to grow in the control containers (Co) than in the containers with garlic (No) on all sites of the lake. The mean ratio of Co/No ranged from 1.94 (site 3) to 2.22 (site 2). Therefore, garlic Nitellopsis obtusa limits the growth of the fungus species in the water bodies.