Tips on Cycling a New Guppy Tank

Cycling With Fish

• To begin cycling, add a few hardy fish, such as white clouds or zebra danios. These starter fish are hardy enough to tolerate high ammonia and nitrite levels, while providing the waste needed to begin the growth of bacteria. Add no more than two or three fish for a 10 to 20 gallon tank. Feed fish daily, but do not overfeed them. Add just enough food for the fish to eat completely within a few minutes. Overfeeding will result in decaying food particles, which will influence the cycling process. Perform a 10- to 15-percent water change every couple of days and test the water regularly using a home test kit. Once the ammonia and nitrite levels are at trace amounts, your tank is fully cycled and safe for guppies.

Cycling Without Fish

• To cycle without fish, you may add commercial starter bacteria to your tank or add gravel or decorations from an already cycled tank, to introduce bacteria, followed by adding ammonia in small amounts to encourage bacterial growth. Add 1 tsp. to 2 tsp. of pure ammonia per 10 gallons of water. Let sit for one hour and check the ammonia levels using a test kit. Repeat as needed until ammonia levels indicate 3 mg/L to 5 mg/L. Check ammonia and nitrite levels once a day. A drop in ammonia levels indicates bacterial growth, which means your tank has begun to cycle and you can begin adding 1 tsp. of ammonia to the water daily to encourage continued growth. Continue testing the water until nitrite and ammonia levels register at trace amounts. Once trace levels are established, stop adding ammonia to the water and perform a 50 percent water change. Let the tank sit overnight and retest the levels again. If they still register at trace amounts, your tank is cycled and ready for guppies.

Adding Fish

• It's important to not overwhelm the system by adding too many fish at once. Add no more than a few guppies per week to keep the system in balance and allow bacteria to grow enough to keep up with the addition of the new guppies.

Maintaining a Healthy Tank

• Several factors can cause an imbalance in a cycled tank. Chemicals used to treat diseases, for instance, can often kill bacteria established during cycling. If possible, move sick fish to a separate tank for treatment. Overfeeding fish is another common cause of a cycled tank becoming imbalanced. Also, dead fish or snails left in a tank for extended periods of time will cause a spike in ammonia and nitrite levels. Check your fish regularly and take care to remove dead fish or snails from your tank as soon as you see them.