Zooplankton: Microscopic animals that drift in the water column, such as rotifers, daphnia, and copepods.
Insects: Aquatic insects, such as mayflies, caddisflies, and midges, are an important food source for many river fish, especially during their larval stages.
Algae: Some river fish, such as carp and sucker, are herbivorous and feed on algae that grows on rocks, logs, and other surfaces in the water.
Small Fish: Larger river fish often prey on smaller fish species, such as minnows, darters, and shiners.
Crustaceans: Crayfish, shrimp, and other crustaceans are a common food source for many river fish.
Mollusks: Snails, clams, and mussels can be eaten by river fish that have the ability to crush or break their shells.
Aquatic Plants: Some river fish, such as the grass carp, are herbivorous and feed on aquatic plants like duckweed, water hyacinths, and cattails.
Scavenging: Some river fish, such as catfish, are scavengers and will feed on dead or dying fish, insects, and other organic matter.
The dietary preferences of river fish can also vary depending on their size, age, and the season. For example, larger fish may be more likely to prey on smaller fish, while younger fish may rely more on zooplankton and insects. Seasonal variations in the availability of food sources can also affect the diet of river fish.
