My fish tank tested out with a ph of 7.5, a nitrite of 0 a ammonia of 0 and a nitrate of 0. It is a fifty five gallon tank that has been set up and running with two fish in it for a year. I recently bought two more, and quarantined and placed them in the tank. It has been three weeks of the tank running, and tonight when I went to test it, it tested out like that when the nitrite, nitrate, and ammonia had all tested out with some in the tank. The ph had been a steady 7.0. I don't understand what is happening, but I do know that one of my fish that I had for two years is now dying in my tank.

Ok, I just retested and I think maybe the thing is alright after all. I have had a rough day today at college and I am extremely upset over Patches dying as I have owned him for two years, and he is near and dear to my heart. Here are the new readings.
Nitrite 0
Nitrate 5.0
Ammonia 0.25
PH 7.5
Patches has suffered from SB for two years now, so it's not really a surpise that he's going now.

Ok, I just retested and I think maybe the thing is alright after all. I have had a rough day today at college and I am extremely upset over Patches dying as I have owned him for two years, and he is near and dear to my heart. Here are the new readings.
Nitrite 0
Nitrate 5.0
Ammonia 0.25
PH 7.5
Patches has suffered from SB for two years now, so it's not really a surpise that he's going now.

Has your tank cycled yet? Someone please correct me if im wrong but if your tank is cycled your Ammonia should be at zero and your Nitrate just a bit higher. Your fish are not in danger yet but i would keep an eye on your Ammonia.

I would do a water change and get that ammonia down to ZERO!

I certainly agree with the water changes.Any time that you are having ammonia readings on a cycled tank is dangerous,no matter how much ammonia it is.

Okay, I'll do a water change when I get home this evening. The tank has been set up for a year and I have never done more than a fifty percent water change and that only once. I change the water about one fourth of the tank every three weeks, and I have been testing regularly. I'm wondering if the introduction of two new fish into the tank didn't cause this thing with ammonia.

That makes sense to me. Your cycle was set up for fewer fish than you had, adding two at a time means you've added a significant amount of waste that the bacteria weren't ready for. There just weren't enough of them there to handle the load.

I agree, by adding two fish suddenly, you may have gotten a bump in your cycle.