Nutrition
The nutrition intake of the Fantail Darter does not include much variety, although season, age, and size play factors. A typical diet includes a variety of aquatic insects, copepods, amphipods, cladocerans, and isopods, (orders of crustaceans), hydrachnids, and gastropods, and nymphs that cling to the underside of rocks (Kraft, C.E., D.M. Carlson., and M. Carlson. 2006). The insets consumed includes dipterans, plecopteras, and a small portion of mayflies, most commonly being the Baetis genus but also Stenonema, and Caenis. Caddisflies insects make up almost half of the Fantail Darter's diet, including genuses Hydropsyche, Cheumatopsyche and Chimarra. and dipterans. Along with these major food sources, fish eggs, mites, nemotodes, water, and both larvae and adults of the beetle genus Stenelmis are additional forms of food for this fish. It is likely that these final sources are consumed incidentally due to internal parasites of larvae (Adamson, Scott W., and Thomas E. Wissing. 1977).
Although this diet is mostly consistent throughout this species, size and age do affect it's food intake. Medium-sized fish, more than 15 mm in length eat the greatest amount of variety. Young Fantail Darters tend to mostly feed on mayflies and midge larvae, while adult fish add other larger insects to their diets (Kraft, C.E., D.M. Carlson., and M. Carlson. 2006).
Food preferences for the Fantail Darter varies due to prey availability, vulnerability, and quality. These factors are dependant on habitat characteristics and behavioral traits. Some of these aspects include turbidity and temperature, as well as swimming, crawling, and burrowing. The quality of the available food influence the fish's diet. Food that lacks a hard exoskeleton tends to be consumed more often by this fish (Adamson, Scott W., and Thomas E. Wissing. 1977).
In respect to the above factors, the Fantail Darter typically feeds during early morning and late afternoon. It consumes the largest amount of its diet around 5 pm each day. The Fantail Darter is a visual feeder, therefore it typically does not feed during non-daylight hours (Adamson, Scott W., and Thomas E. Wissing. 1977).
Temperature also plays a role in the Fantail Darter's digestion process. When it digests its food, the gut has both the newly captured food as well as previous food undergoing the various stages of digestion. The lower the temperature is in the darter's gut, the faster the rate of digestion will occur (Adamson, Scott W., and Thomas E. Wissing. 1977).