The Aquarium Nitrogen Cycle
What's the Aquarium Nirogen Cycle and How Important is it??
Put simply, if you understand and work with the nitrogen cycle, your fish will stay healthy and you'll lose very few. In the wild this really isn't that important, because ammonium and nitrite is diluted by billions of gallons of water. In the aquarium, even a tiny amount of nitrite or ammonium can be at a concentration (due to the low water volume) to injure or even kill fish.
If you don't understand or work with the principals of the nitrogen cycle, you'll be very lucky to escape fish deaths, and could easily lose all your stock.
The Aquarium Nitrogen Cycle works in 3 stage. Fish waste, uneaten food, dead plants etc all decompose and breakdown into ammonium. Ammonium will kill fish even at low concentrations. In an established aquarium there in sufficient quantities of a friendly bacteria to immediately convert this into Nitrite.
Nitrite is still toxic to fish. Again in an established aquarium their is sufficient friendly bacteria to immediately convert any nitrite into nitrate.
Nitrate is relatively harmless unless it reaches high levels of concentration.
Nitrate levels in the aquarium are managed by regularly conducting partial water changes.