The majority of darters can be sustained on frozen foods alone, with bloodworms being the universal favorite. Frozen glassworms are a close second, though their tendency to float after freezing means that the darters have to learn to feed from the surface. Darters tend to do this over time, but obviously the tank should be checked after feeding to be sure the food is being consumed. Many darters feed on frozen brine shrimp, although it may not be as nutritious as other frozen foods. Frozen Daphnia is virtually worthless, though live Daphnia is great for the fry and smaller species.
Live food is always good when obtainable, but several caveats are in order.
The most widely available live food from the pet shops is blackworms, which if properly cleaned and used with a worm feeder can be an excellent conditioning food. They can carry diseases, however, and when unconsumed they can burrow in the aquarium gravel, die, and pollute the tank and increase the chances of disease in the aquarium. Vigilant gravel cleaning and cleaning the worms often lessen the chances of infection. Scavengers can be great aids in consuming uneaten food. Anything from suckermouth catfish to madtoms will assist in cleanup duties and prevent worms from burrowing into the substrate.