The most basic rule of feeding fish is to feed them as much as they will consume in 5 minutes and no more. This can be repeated 2-3 times daily, but generally this level of feeding is unnecessary for adult fish. 1-2 times per day is usually adequate, with at least one day off each week.
One of the main causes of poor water conditions, algae, and snail outbreaks in an aquarium is overfeeding. Uneaten food sinks to the bottom and if not consumed will soon decay and foul the water. Snails, catfish and loaches can all help to remove uneaten food, but it is far better to underfeed. Fish can survive very long periods with NO food, and this is normal for many species. Slightly hungry fish will show themselves more and will benefit from a cleaner tank.
Most people are familiar with the standard aquarium foods, in flake, pellet, and tablet forms, but there are a whole range of other choices: from living worms and flies, to frozen bloodworms and beefheart recipes. All have a place in a varied fish diet, and will help induce spawning, maintain health, colour and above all happiness of your fish!