Types of food
There are many different types of food. There is live food, pellets, freeze dried, frozen etc.
Pellets are a great food form because they pack many of the necessary nutrients. The only problem is, not all fish will eat pellet foods. Some fish, such as the Copperband Butterfly, are very picky eaters and will sometimes only eat live copepods in your tank or worms such as blood worms or black worms.
Common foods in the frozen section include mysis shrimp, blood worms, and brine shrimp. Hikari makes high quality frozen fish foods.
One of the most common pellet foods is New life Spectrum.
Keep in mind:
Small, frequent feedings are best. However, this is not practical for all people so a typical rule is to feed no more than what the fish can consume in 5 minutes. Of course, this varies widely based upon the number of fish and size of fish.
Our fish seem to gobble-up everything in 5 secs! If we fed enough food to take 5 minutes to consume, we would go broke quickly and likely pollute the tank just as quickly.