The creek chub, Semotilus atromaculatus, is a widespread freshwater fish inhabiting streams and rivers across much of North America. These fish display a dark brown body with a distinct black lateral line extending from the nose to the tail, reaching lengths of 5 to 7 inches, with some growing larger. Their robust nature allows them to thrive in various stream environments, making them a common and adaptable part of their ecosystems.
Primary Food Sources of Creek Chubs
Creek chubs are generalist carnivores with a highly adaptable diet, consuming a wide array of food items found in their aquatic environments. Their diet primarily consists of insects, both aquatic and terrestrial. Aquatic insect larvae, such as mayflies, caddisflies, stoneflies, and chironomids, are common prey, particularly for younger chubs. Terrestrial insects like ants, beetles, grasshoppers, and flies also provide a substantial energy source when they accidentally enter the water.
Beyond insects, creek chubs consume other small aquatic organisms, including crustaceans like amphipods and copepods, as well as worms and mollusks. Larger creek chubs also prey on smaller fish, including the fry of various species and even younger creek chubs, demonstrating cannibalism. While primarily carnivorous, they also consume some plant matter, such as algae and plant tissues, often incidentally. Detritus, or decaying organic material, may form a minor part of their intake.
Factors Influencing Their Diet
A creek chub’s diet changes based on environmental and biological factors. One influence is the fish’s age and size; juvenile chubs primarily feed on smaller invertebrates and insect larvae. As they mature, their diet diversifies to include larger prey; individuals over 81 mm become primarily piscivorous, feeding on other fish. Their mouth size, or gape, also limits the maximum size of prey they can consume, particularly in younger stages.
Seasonal changes also shift the creek chub’s diet due to food availability. For instance, terrestrial insects are more abundant during warmer months, leading to increased consumption of these items. In contrast, aquatic larvae and other benthic invertebrates might be more consistently available in colder seasons. The specific habitat, such as a fast-flowing riffle compared to a slow pool, also dictates the types and abundance of prey available.
Creek chubs are highly opportunistic feeders, consuming whatever food is most readily available. This adaptability allows them to thrive in diverse conditions and fluctuating food supplies. They are known to actively forage for periods, then wait for drift items to pass by, consuming a wide range of surface and benthic organisms.