How Much Should I Feed My Fish? It’s always best to underfeed, especially in new aquariums, as uneaten food can cloud your water and cause dangerous rises in ammonia and nitrite levels. A general rule of thumb is to feed only what your fish can consume in 2 to 3 minutes. When in doubt, start with a tiny quantity and observe how fast your fish consume it. If it is completely consumed in less than 2 minutes, give them a little more. It won’t take long to figure out how much food to give them at each feeding. Remove any food that remains after five minutes with a siphon hose or net. What part of the water column your fish feed in. Fish can be: Surface feeders Mid-water feeders Bottom feeders Most fish will learn to take food wherever it’s available, but some specie of fish like shy fish may wait until food drifts into their “safe zone”. These fish may need to be target fed, meaning directing food right to them. Flakes and some pellet foods typically linger at the surface for a mi...