Okay, you don't give ammonia levels. I'm afraid they're bad. Get the ammonia tested also, so we've got a better picture of what's going on. However, the presence of nitrite indicates the tank either isn't fully cycled, or the cycled has been interrupted somehow. Take some time and read about the nitrogen cycle, and then try to figure out which of these it is. If you're interrupting the cycle by overfeeding, underfiltering, washing your filter media in tap water, etc., then you want to fix that so that this isn't constantly happening. The nitrate is WAY high, which means one of three things: Your tank is over stocked, you're not doing enough water changes and gravel vacuuming, or the nitrates are really high coming out of your tap. Try testing your tap water and see what you get. The only way to remove nitrate is through water changes; there's no bacteria present that eats it and converts it like ammonia and nitrite, so this usually points to needing more waterchanges. This is only going to increase as the fish get larger. Be sure you're not overfeeding, as well. So, basically, you've got to get the cycle back on track to where your ammonia and nitrite are zero, and nitrates ideally below 20, but some people say below 40.
EDIT: If nitrates are high out of the tap, you may need to switch to RO/DI or something like that, but this is rare.