How much should you feed your fish?

To answer this question, actually there is no definitive rule on how much you should feed your fish. One of the main reason is there is too many factors involved.

Usually I apply a theory of feeding 2 - 3 times a day, give an amount of feed as much as your fish can eat in 3 minutes. If there is too much leftover after that amount of time we have to reduce the amount of feed. This theory can be applied to beginner or community tanks but if you deal with breeding tanks, single species or hospital tanks, you should be more careful with how to feed your fish.

There are some important things to remember about fish feeding habits. In nature, most of them usually have a hard time finding food, and through evolution they have been "programmed" to eat as much as they can fit into their bellies whenever they find some, because they never know when the next meal will be found. In a tank, we do know when their next meal will come. Therefore, it's up to us to control the amount they get. Feeding them until they seem satisfied is not a good idea. Fish are expected to spend most of the day feeling hungry and searching around for little bits of food.

A common mistake made by beginners is to overfeed because their fishes seem to be desperately begging for food every time the owner approaches the tank, and he decides to satisfy their appetites every time. A hungry fish is a healthy fish...if they don't come up to you when approach in the morning, that's when you should start worrying.

As another evolutionary defense, fish seem to adapt to the availability of food, by adjusting their growth rate. When they live in a place with more food available they respond by growing fast, and vice versa. Because of this, I believe that the actual amount you decide to offer isn't as important as maintaining the same criteria throughout their lives. So the ideal situation would be to setup your tank, populate it with young fishes, define a reasonable feeding criterion and stick to it.

Finally, keep in mind that it's way easier to weaken or even kill your fish by overfeeding (because it spoils the tank water) than by making them starve to death.