How to Cycle With Guppies

New fish added to a fish tank or aquarium need to have the appropriate living conditions to survive in smaller quarters. To prepare the tank or aquarium, you must first cycle the water to get a healthy amount of bacterial growth that will digest ammonia and turn it into nitrite. The cultured filter will then turn it into harmless nitrate. Although there are several cycling options to get the appropriate bacteria level for new fish, using guppies to cycle the water is an economical option. The guppies can turn new aquarium filters from ineffective up to a cultivated bacteria colony.

Things You'll Need

  • Water
  • Fish tank or aquarium
  • Dechlorinator, chlorine neutralizer or chlorine remover
  • 2-3 guppies per 10 to 20 gallons of water
  • Water testing kit
  • Cup
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Instructions

    • 1

      Fill your fish tank with water. Treat the water with a dechlorinator, also known as a chlorine neutralizer or a chlorine remover, to get rid of the chlorine content. Read and follow the product instructions for specific directions, as each product is slightly different. If you don't treat the water, the chlorine content will kill the bacteria you need to cycle your fish.

    • 2

      Add two to three guppies to a 10 to 20 gallon tank. Add more or less, depending on your tank size.

    • 3

      Test the water the day after you add your fish with a liquid test kit. Fill a test tube from the kit with water from your tank. Add the manufacturer recommended amount of drops to the water to test the ammonia levels within the water.

    • 4

      Do a water change every couple of days. If your ammonia and nitrite levels are between .25 and .5 percent, do up to a 50 percent water change. If the ammonia level is more than 1.0 percent, change 75 to 80 percent of the water. To do a water change, remove water with a clean cup and replace with dechlorinated water.

    • 5

      Repeat the water testing process until you reach the appropriate ammonia and nitrite levels. This process will take approximately six to eight weeks. Nitrate readings are nontoxic and are a good sign. Once the ammonia and nitrite levels are at zero or only trace amounts, your tank or aquarium is properly cycled and you can add more fish. Add fish a few at a time so as to not overload the filter. Introducing too many fish at once can make the ammonia and nitrite levels raise too quickly.