Jellyfish blooms pose multiple threats to wild fish. Yet, we still know little about how blooms impact fitness-related behaviours of fish caught within their areas of effect, e.g. for littoral fish that are not able to relocate to avoid incoming blooms of stinging jellyfish. Here, we documented the behavioural impacts of freshwater jellyfish (Limnocnida tanganjicae) blooms on a territorial cichlid (Variabilichromis moorii) as well as on the wider community of cichlids in a shallow-water rocky habitat of Lake Tanganyika. Compared to non-bloom conditions, V. moorii individuals reduced their swimming and territory defence activities during jellyfish blooms (each by ~ 50%), but not their foraging or affiliative behaviours. Despite this reduction in activity, V. moorii could not entirely avoid being stung and preferred to remain closer to the rocky substrata as opposed to the more open demersal zone. Many other fishes similarly hid among the benthic substrata, changing the composition of the fish community in the demersal zone during bloom conditions. Reductions in activity could have multiple fitness-related implications for individual fish. Understanding these behavioural consequences is an important topic of research as blooms are predicted to increase in severity in the future especially along coastal habitats.