Originally Posted by rowansmomma
Its still in its cycle......it will take a few more weeks to balance out.
In case no one has explained the cycle to you, when you get a new tank, there's no bacteria in it. You can add it with the bottled stuff like cycle, but the bottled bacteria is not terribly active and takes some time to establish itself.
When you first add fish, the waste they produce contain ammonia and cause certain strains of bacteria to grow that will consume the fish waste and food refuse and turn the ammonia into nitrites. When you get an ammonia spike, this means that there isn't enough of the type of bacteria that consumes ammonia to process the waste being generated by your fish. Eventually, the presence of ammonia causes the bacteria to grow and it catches up with the ammonia and turns it all into nitrites.
Other bacteria will consume nitrites and turn it to nitrates. However, they will not begin to start to colonize until nitrites are present. This is why you get a nitrite spike.
To minimize the effects of ammonia and nitrite spikes, it is usually recommended that you add only a couple of fish to a new tank. After the tank appears to have cycled effectively, then you slowly introduce more fish, like a couple at a time per week. This ensures that the bacteria levels catches up with the fish.
Since you got your tank during Christmas and already have 12 fish, I'm guessing the tank has not had enough time to establish the colonies of bacteria you need. As pp suggested, feeding them less will lessen the ammonia loads, thereby lessening the nitrite loads. Other than water changes, and adding live bacteria, there's not much else you can do except wait it out for the bacteria colonies to establish themselves.