Automatic Fish Feeders (Auto Feeders) are used by koi keepers to accelerate the growth of their koi. Carp (and therefore koi) are grazers, and will feed continuously in a natural environment, eating little and often. This is hard to replicate, when you have to work, for example. 

By setting an auto feeder to disperse pellets through the day, you can give your fish more food, and more food means more growth. Feeding this way instead of 2 large feeds per day increased water quality and digestion also. 

Auto feeders can be mains powered, or use a battery, and some even use solar power.