Guides > Cycling your tank before adding live stock
Cycling Your Aquarium & Adding Fish

The Nitrogen Cycle

Before adding your chosen fish, your tank must "cycle" or become biologically stable. Cycling is the process where a nitrifying bacteria colonizes in your filter and gravel. This bacteria's job is to detoxify the wastes created by your fish. You will notice that within the first few weeks by testing your water, ammonia and nitrite levels will rise in the tank and slowly decrease. Also during this time you may see the water in the aquarium start to cloud or look grey. Do not worry, this is natural, the cloudiness will pass quickly on its own, or you can add a bacterial supplement such as Stress Zyme or Stability to help lower ammonia levels and aid in the cycle.

Fish can be added about three days after setting up your aquarium. This time allows the temperature and pH to stabilize. The first fish you should add are starter fish. The cycling process is very stressful for most fish so we recommend hearty starters that can handle adverse conditions. These are usually danios, or white cloud minnows, small, non-aggressive fish that come in several colors. These fish will eat and create waste, spurring the growth of the beneficial bacteria that will help complete the cycling of your aquarium.

While your aquarium is cycling do not change any water or clean out your filter media. The loss of bacteria will set your cycle period back, increasing the time you have to wait before adding other fish. Your tank will be completely cycled when ammonia and nitrite both test at zero and nitrate tests low. This can take anywhere from 3 to 8 weeks. The key here is to be patient.