Habitat

The Mud Darter is a shallow water fish that inhabits the Mississippi River and its tributaries from Minnesota all the way to Texas and Louisiana, but also occurs in inland streams in Illinois and Kentucky. The adults in the population prefer to inhabit the gravel and clay bottoms of streams with moving water and some form of shelter like tree roots or rocks. Young Mud Darters however, are found more often in smaller and quieter pools slightly downstream from the adults (Cummings et. al., 1984).

Studies have suggested that the reason Mud Darters inhabit these shallow and often moving bodies of water is due to a need for a high amount of dissolved oxygen. The movement of water along with temperature and depth play an important role in dissolving oxygen in water, so this hypothesis is not too far fetched. In 1978, a study was conducted on the genus (Etheostoma) and concluded that there is indeed somewhat of a relationship between dissolved O2 levels and the fishes found there. Fish like the mud darter that are only found in shallow moving water have an intolerance to low oxygen levels (hypoxia), which explains why their distribution is so limited. In turn, more common members of the same species that are widely distributed and great in number have more of a tolerance to hypoxia, which allows them to exist in more diverse habitats (Ultsch et. al., 1978).

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