How long before you put fish into a tropical fish tank?

If it is a new tank, it will have its first ammonia cycle. Ammonia can be a huge problem and will most likely kill your fish. Set up your tank, Fill with tap water, Condition the water and put in a filter. Wait a whole week with the filter running then when you go to a pet store to buy fish, take a water sample for the pet store to test your water. So you know that the water wont kill your fish. Don't put the water from the pet store into your tank as it may not be as healthy as your new tank water. Before you put the fish in, Float the bag on top of the water for 20 minutes to get the fish used to the water temperature.

Hope this info helped!