Nitrite, nitrate spike in established tank - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 7 Old 07-28-2007, 04:28 PM Thread Starter
Nitrite, nitrate spike in established tank

Everyone's going to think that I have a knack for things going wrong in my tanks (I think this is my 15th post in the Emergencies thread), but here goes anyway. I would rather admit to a problem and get it fixed rather than pretend I know exactly what I am doing.

I had two twin-tailed goldfish in a 5.5 gallon tank. Moved them to a larger tank and put three guppy fry into the 5.5 The tank has been established for months now, and goldfish are notorious for producing ammonia, so I would have thought that three tiny fry would have been a piece of cake for the filer to handle.

All went well for 48 hours until this morning - one fry was dead, and the nitrite was at 10ppm with the nitrate at 20ppm. I have never had such a high reading in any tank, even during the cycling process! What went wrong? I vacuumed out the gravel and did a water change and am planning to do water changes until I get the levels corrected.

I think I overfed them; I crushed up a few tropical flakes for them twice a day, but when I vacuumed this morning there was quite a bit of debris at the bottom. It was hard to see what they ate and what they didn't since the flakes were powderized. Could that have caused such a huge spike? Or could the biological filter have died since there was such a drastic change between two fancy-tailed goldfish and three itty bitty guppies?

Best wishes for your fishes!
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post #2 of 7 Old 07-28-2007, 04:52 PM
willow's Avatar
well i'll go out on a limb here,
i reckon the bacteria died off.howevwer i could be
wrong(wouldn't surprise me).
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post #3 of 7 Old 07-28-2007, 11:16 PM
JouteiMike's Avatar
What is the temperature and pH of the tank?

I would vary the fry's diet. Baby brine shrimp and hard boiled egg yolk are some good food choices. It is important to feed the fry often, (more than twice a day) but small amounts.

How long have the fry been in the tank? What kind of filter are you using?
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post #4 of 7 Old 07-28-2007, 11:43 PM Thread Starter
The temperature is about 78 at the hottest point of the day and about 74 at night. The pH is about 8.0 - a little high, but I try to acclimate my new fish and I would rather not mess with altering it.

I have a Rena Stingray 5-gallon filter on the tank.

I bought the fish on Thursday of this week, so I have had them about three days. I call them fry because they are only about 1/2-3/4 inch big. They're supposed to be feeder guppies, but I just wanted a few fish for my little boys to enjoy so I didn't want to spend a lot on full-grown fancy varieties.

I will try to vary their diet a little more. How often should I feed them? 3 or 4 times? This is my first time with such tiny fish.

Best wishes for your fishes!
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post #5 of 7 Old 07-29-2007, 04:05 AM
Falina's Avatar
The only thing I can think of is that with the goldfish being such big waste producers and the fry clearly not being it was almost as if you had emptied the tank altogether and so the bacteria died off. Then with the food going in maybe it took 48h for it to start decomposing and so this is where you got the readings. The waste alone from the fry probably wasn't enough to keep the tank going, so the tank waited on the food decomposing?
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post #6 of 7 Old 07-29-2007, 09:58 AM
JouteiMike's Avatar
I would feed them as often as you can for the first few weeks.

And about the water parameters, I'll have to agree with other responses. It's likely biological filtration died off from the drastic absence of substantial waste.
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post #7 of 7 Old 07-29-2007, 11:37 PM Thread Starter
Yes, I think the bacteria died off as many of you mentioned, and the extra food that was not eaten that fell to the substrate only added to the spike. Thanks for confirming my suspicions.

After several water changes, things are much more balanced now. I will keep close tabs as the fry continue to grow.

I am also feeding them frequently and trying to vary their diet more. All this advice has been invaluable!

Best wishes for your fishes!
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