Algae and cyanobacteria communities were monitored and associated with nutrients and anthropogenic activities in bays of the Bukavu basin of Lake Kivu (DR Congo). The monitoring was done to investigate the impact of Nile tilapia (Oreochromis niloticus) cage culture on algae and cyanobacteria communities in selected bays. Sampling was carried out from February to September 2021. In all selected bays, a standard quantity of water was filtered through a 10 mu m mesh phytoplankton net for planktonic algae, while the epiphytic algae were scraped from cage net walls and macrophytes accordingly. The results revealed higher abundance of pollutiontolerant algae (diatoms) and cyanobacteria in the pilot bays than in the control bay, suggesting impacts of tilapia cages on the aquatic communities. The study detected a significant difference (p