Nitrite levels...?

Question

I posted a couple of days ago about my missing Oto... I have still not found him, or his remains :( anywhere....

The day after I 'lost' him, I carried out a clean/water change - before I done this, I tested my water levels...

The nitrite (NO2) was reading 0.8, when it has neven been over 0.3 before....

So, done the clean/water change, and today, 2 days later, I've done another water quality test... my nitrite levels are still showing as 0.8... Nitrate and Ammonia are fine...

I have no idea why the level has gone up, and is still up after a water change.... I'm wondering if my little missing fella IS still in the tank somewhere, rotting away.... would this cause the nitrite levels to go up?

I know the level isn't too dangerous at 0.8, but I don't want it to stay like this.... could it be the missing Oto causing this, or something else??

Note to Sarah: My Oto has EVERY business being stocked in my tank, because my tank IS fully cycled, I've had it running now for at least 7 months... successfully until this one recent problem.

Note to Sarah: My Oto has EVERY business being stocked in my tank, because my tank IS fully cycled, I've had it running now for at least 7 months... successfully until this one recent problem.

Answer 1

I think in order to answer your question adequately, it's important to consider how old the tank is.

If this is still within the first two months of operating, the tank may still be cycling. This is where the bacteria to convert the ammonia and nitrite to nitrate are becoming established. It can also happen when you've used an antibiotic recently, causing the death of the good bacteria and your tank needs to "recycle" itself to bring them back to their normal levels. I would consider this to be a good possibility since you're getting persistent nitrite readings.

If your tank is beyond the two month mark and you haven't been using antibiotics, you need to find out why you have the nitrite readings. Although 0.8ppm isn't fatal to most fish in a very short term, it (as well as lower levels) can be if the fish are exposed for a long enough period. Otos can be particularly sensitive to water quality, and it's best to add these only after the tank has finished cycling (meaning consistent readings of ammonia and nitrite are 0).

Some reasons you might get nitrite are that it's present in your water source (have you tested your tap water as well?), the death of a fish, overfeeding, and inadequate cleaning of the gravel (the wastes continue to decompose, giving off ammonia). A gravel vac should be used at every cleaning to siphon wastes ot of the gravel rather than just "dipping" the water from the tank. And cleanings should be done at around 25% every week (although the filteration and stocking level may change the exact amount needed). Your testing may also be off, especially if you use paper test strips - if in doubt, get a second source to double-check your results.

That you can't find the oto may not be that unusual, especially if there are other fish (or snails, shrimp, or other animals) in the tank. It can be surprising how quickly a dead fish can be consumed, especially when it's the size of an oto.

Answer 2

How long has this tank been set up? If your tests are showing nitrite readings, it sounds like your tank isn't cycled yet and you're in the middle of a nitrite spike. A fully cycled tank shows ZERO ammonia and ZERO nitrites, and should also be showing nitrate readings. If you've got .8 nitrites and zero nitrates, you're not cycled.

By the way, the level is indeed VERY dangerous at .8, as nitrites are extremely toxic to fish at any level. You need to be doing daily water changes to keep your nitrites as close to zero as possible until your cycle finishes, or you're going to be losing a whole lot more fish than just an Oto (which has no business being stocked in an un-cycled tank to begin with).

I'm sorry if this seems harsh, but you need to act very quickly to try to save the rest of your fish.

Answer 3

over feeding and dead fish can cause your nitrite levels to rise,all you can do is look again for a dead fish and do a 10 percent water change and gravel clean daily for a week and keep testing your levels in your tank.
high nitrite levels are normally a indication that your over feeding