Two days ago I checked the water. Ammonia 0. Nitrites close to Zero. Today, the Oscar was "hiding" in his terracotta pot, which he seldom does during the day. Since this was very unusual for him, I re-tested the water.
Ammonia 0. NITRITES 3.3! I freaked out! How in the world did my nitrites get so high so fast?! I immediately did a 45% water change. The day I checked the water, I also did a 20% change, and vaccuumed the gravel. Today the gravel looked good, so its not like the tank was dirty or anything. But the Nitrite level was way too high! I had done nothing out of the ordinary to either the tank nor the water, so I can't figure this one out. When I replaced the water today, I used the usual amount of water conditioner, plus a little Cycle, and small amount of Amquel Plus. I will test the water in a few hours, to see if the levels have dropped. Does anything in particular cause Nitrites to skyrocket like this? Please help, so I can cure the problem. Thanks! 1533 my time on Saturday.

How long have you had this tank up and running? did you do a full cycle before putting your fish in?

Tank has been running a little over a month. Could it be just a "cycling" thing? Water changes will continue. Thanks.

It could well be that your tank isn't cycled fully yet. I would reduce the feeding straight away, you could even just feed your fish every other day. If your nitrites are high, you want to reduce the amount of waste going into the water.

Also, how many fish have you got in your tank and how big is it and what kind of filtration have you got?

55 US gallon, one 6-inch Oscar only, not overfed, no plants, FX5 filter running micropads, biobeads, etc. Normal setup. (I'm also leaving for five days. I plan on doing a 50-70% change before I leave, and hope things will remain safe while I'm gone...) Thanks

I can only put it down to your tank not being cycle properly. It normally takes around 6 to 7 weeks. These things do happen occasionally. It happened a couple of times on my 125 gallon tank. However, I put this down to having too many Oscars. Having said that, I did have two canister filters running with loads of bio location. As quickly as it happened, it disappeared. So I never really knew why.

I would strongly advise you to get a product such as "Prime" this will at least detoxify the nitrite and make a little safer for your fish. Apart from that, I can't you be a conclusive answer to why this happens.

guava i agree with glen ofl and yourself .............a full fish cycle takes about 45 days to complete from the first ammo reading NOT FROM when you put water in it ...i work it out to be on average 5-7 days in a new tank to get the ammo reading ..this is why most people put ALL their fish in a new tank after 5-6 days because they test and say "i have no ammo or nitrite" so i must be cycled....anyway take the first 7 days off 30 for the month you say you have been running it you are left with 23 days ..the ammo does not start to fall and the NITRITE rise until 20 days after the first ammo is present..then 10 days after the nitrite starts to rise it peaks and starts to fall for 10 more days .......so if you work out in days whare you are in the cycle from the start you will see that you are allowing a day or 2 for the first ammo reading (because i didnt know when this was exactly) you are 5 days from the NITRITE PEAK ....then 10 more days for it to fall to zero and your NITRATES TO PEAK..you will see your nitrite rise for 5 more days then start to fall so you need 40-50% waterchanges DAILY for 15-17 more days then you will be fully cycled ...but your nitrites will rise higher for 5 more days if i am correct heres a simple graph for you to see what i mean

LOOK AT THE 23-25 DAY POINT ON THE GRAPHS YOU CAN CLEARLY SEE YOUR NITRITE RISE......hope this helps

i have been guiding oscarruss through a cycle from the very start, daily for just over a month and from the point of him adding fish to now its 4 weeks and only now is he getting NITRITE rising????????? check it out

www.oscarfishlover.com/index.php/Emergen...elp-/20202-HELP.html

Nitrites now reading <.03
2038 my time Sat.
Thank you to glen, bgh, and ofl for your help! The advice (and graphs) were very helpful! I will continue to do 40-50% water changes. I could have sworn the tank had cycled, but I guess not. I appreciate the input from all concerned. Your expertise is invaluable. "Pints all 'round"! Cheers!

That'll be a JD and coke for me thanks