Fish still dying after new tank levels stablise

Question
Hi,
I set up a new tank, and I made the mistake of not leaving it long enough to settle before adding the first fish. After a few days 5 of the 9 neon tetras died. I bought a thermometer and a testing kit (Tetra 5-in-1). Everything is normal (i.e. nitrites and nitrates almost 0, pH about 7, hardness about medium), all the levels and temperature are as they should be but the fish are still dying.

Obviously I don't know what the levels were when the first started dying but I was wondering how long after nitrite levels spike the affects are still felt by the fish?

Thanks

Answer
Hi Tim,
As far as I know, I don't think the Tetra 5-in-1 has a test for ammonia, which is a bad thing because you really need to know your ammonia level whenever your tank is recently setup as ammonia is the biggest killer of aquarium fish.

Your nitrites may also be responsible for some of the fish loss. But knowing your ammonia level is quite important to. Knowing this will also help you know how far along your tank is with cycling. If you see that your ammonia and nitrite are dropping then you know your almost there with cycing. Especially if the nitrate levels are building up, then you really know if your tank is almost cycled, it's getting there.

But what I can tell you know is the most important thing your fish need---water changes. Water changes will provide immediate relief from poor water conditions and are the best  remedy for ammonia or nitrite spikes. It will not stop the cycling and its vital for keeping your fish healthy. Whenever your ammonia or nitrites gets above safe bounds, (test kits usually indicate) immediately do a 50% water change.

Both ammonia and nitrite can have lasting damaging effects on the fish if they are overexposed for long periods. Water changes can help this. It's also best to try to use hardy fish for cycling. Neons unfortunately aren't the best cycling fish, they cannot hold up to much. Zebra danios, platies, or black skirt tetras are excellent cycling fish. An even better alternative is to fishless cycle, which involves harming no fish at all plus it is much quicker. You can read more about it here-
http://www.aquatic-hobbyist.com/profiles/misc/fishlesscycling.html

This article goes by adding pure ammonia, but many fishkeepers just add a pinch of flake food to their water every day or so to build up the ammonia and get the bacteria colonized.

I really hope this helps, for now, water changes are your fishes best friend until your tank gets established. To help things along, you can buy bacterial additives plus use water conditioners that neutralize ammonia, nitrite and nitrate such as Amquel+ which is a great water conditioner I use.

I really hope this helps, let me know how things are going.
Best of luck,
Karen~