Did I miss where you said what size tank this is? Anyway..... instead of typing and typing, I've cheated and here's a cut and paste from a decent website. And don't forget to read all of the "cycling" information on this website. It's very valuable information.
Didn't I read in one of your posts that you once had a tank but every fish died of ich? Might have been someone else, not sure.
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http://www.firsttankguide.net/cycle.php
For a tank of small community fish, White Clouds or Zebra Danios are good cycling fish; Cherry Barbs or Tiger Barbs are good for a slightly more aggressive tank; or Pseudotropheus zebra is a good choice for an African Cichlid tank. Your local pet shop should be able to point you toward some hardy fish of the type you are looking to keep. Purchase a small number (the number will depend on the size of your aquarium and type of fish and -to a lesser degree- the type of filter) of these fish and introduce them to your
tank. For a ten to twenty gallon tank, two or three small schooling fish or one small cichlid would be more than sufficient. Let the tank sit for a couple of days, feeding your fish carefully to prevent excess food from decaying and fouling the water. There are several reasons that you do not want to cycle your tank with a large number of fish, here are a few:
- Cycling a tank with many fish will produce a lot more waste, which will be stressful to your fish, resulting in higher die-off and greater susceptibility to disease.
- Cycling with a large number of fish will increase water problems incurred during the cycling process.
- Cycling with a lot of fish can contribute to a foul smell coming from the tank.
Every couple of days, do a 10%-15% water change, and after about a week, take a sample of your water to a fish store to get it tested. Most pet shops will test fresh water for a minimal fee, or even for free! If the store you got the fish from won't, check to see if there is another local store that will. At this point, your water should test with high ammonia and maybe a trace of nitrite. If it isn't, don't worry. Just give the tank time.
The cycling process usually takes four to eight weeks.
After about eight weeks, your ammonia and Nitrite levels should be acceptable (about trace levels), and you can add more fish. Do not add more fish until the ammonia and Nitrite levels have
both dropped. Remember to add new fish a few at a time to prevent over-stressing the filter. If you add too many at once, your tank will have to cycle again, yet if you add a few at a time, your bacteria growth rate will just increase for a short time, with minimal effect on your fish.