Basile's post is a good one to read. One thing that I should have mentioned in it that I'll mention here is that fish are opportunists when it comes to eating. They don't have a concept of time, nor do they fully understand that they will be fed regularly even if they recognize you or others as potential feeders. What they do understand is that when they see food that they can get their mouths on, they will do so. So it is easy to overfeed them as they will help you with that notion. Most fish won't pass a meal by thinking,"oh... I'll wait for tomorrow's meal." They just think,"My stomach has room for more therefore I must fill it."