In contrast, the tadpole madtom prefers quieter water flowing over mud, leaves, and other plant material. Even in streams with good water quality, certain species may be absent in sections that do not contain their preferred habitat. Not all 50 species of fish occurring in the study area will be found in every section of stream. The percentage of each stream section covered by the major types of bottom materials is shown in figure 2. These materials differ in their importance to fish as habitat.
Most fish live near larger bottom materials such as gravel, cobble, and boulders.
These larger materials provide spaces where food organisms such as aquatic insects live. Many fish spawn their eggs in nests constructed from gravel, or in holes and cracks in boulders and bedrock. Other important habitats that provide food and hiding places are aquatic plants, fallen logs, and accumulations of sticks and leaves. The percentage of stream bottom covered by different materials in each stream section. As a consequence, the abundance of food organisms and spawning areas required by fish are decreased.