What is an example of a predation interaction in freshwater rivers?

An example of a predation interaction in freshwater rivers is the relationship between the brown trout (Salmo trutta) and the stonefly nymph (Plecoptera). The brown trout is a carnivorous fish that feeds on various aquatic insects, including stonefly nymphs. Stonefly nymphs are an important part of the benthic community in freshwater rivers and streams and serve as a food source for various predators, including trout. Brown trout actively prey on stonefly nymphs, particularly during their emergence from the riverbed to become winged adults. The trout actively chase and capture the stonefly nymphs as they swim near the water's surface. This predation interaction plays a crucial role in shaping the community structure and ecological dynamics of freshwater rivers.