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Hey guys I'm having a bit of a nitrite spike. My system was nearly cycled when I added my goldfish. My nitrite levels were dropping and my nitrate levels were on the rise. I added seven channel catfish I caught a few days ago and ever since then my nitrite levels have been off the scales. My ammonia levels are non existing and my nitrate levels are staying around 5ppm. Any help would be apriciated. I've got to do something quick or I'm gonna lose my fish.

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Get more oxygen in the system. I can't really afford all of this. I really didn't think this was going to be this hard. I've put a lot of work into this project so I don't want to see it fail.

Well, "almost done cycling" and then adding fish is probably an even worse thing to do than cycling with fish from the very beginning.  Patience is would have cost you nothing to follow through, and complete the cycling process...before adding fish...

But now that you have, there's not a whole lot you can do about it. Salting will probably help a bit...but only a bit... since sating is more a pre-emptive strategy for mitigating nitrite poisoning, rather than a cure for an "oh shit" after the fact be prepared to loose more fish. Adding fish right before or during the 'nitrite spike' phase of cycling is about single worst time you could have chosen to add them. Sorry.

Don't used table salt or anything with iodine in it. Buy some solar salt, pool salt, or dehydrated sea water at Home Depot or wherever ...(it's still all just NaCl and it's pretty cheap. DON'T go to the aquarium shop and buy repackaged (NaCl) salt at 20 times the price)...

You need to know your TOTAL SYSTEM WATER VOLUME and not just your fish tank volume.

Salt to 1ppt (yes, that is parts per thousand). For instance...if you TOTAL SYSTEM WATER VOLUME was 175 US Gallons you would need about 662 grams of salt.

Good luck.

Scroll down to the comment and click on the PDF. Read it. It may help solve the mystery   (Table 1 may be of particular interest to you)...

Erik Phillips said:

Thanks for the info. The funny thing is only my catfish have died so far. My goldfish seem fine. My plants are growing fine as well.
Great read. Thanks brother.

That explains so much, and the fact that catfish are both sensitive to nitrite AND salt, makes it especially important to reserve them for only well-seasoned systems.
Ok so say I just leave the system alone ( I've taken my fish out of the system by the way) how long should it take for the nitrite levels to drop?

Anywhere from a couple of days to a couple of weeks.

When the nitrite (NO2) level does drop to around zero, dose ammonia (NH4) to around 1ppm to 2ppm. Wait for both NH4 and NO2 levels to fall to zero. Dose NH4 again to 1-2ppm, wait for both NH4 and NO2 levels to fall to zero...

When you get to the point where you can dose NH4 to within 1-2ppm, and within 24 hours have BOTH NH4 and NO2 levels fall to zero AND YOU CAN DO THIS CONSISTENTLY 3-4 DAYS IN A can consider your system fully cycled and ready for fish.

If you overload your brand-spanking-new-just freshly-cycled bio-filter with too many fish right away (something that apparently many overly enthusiastic new aquapons do), you will probably experience a secondary nitrite spike (the duration and intensity of which is usually less than the first NO2 spike)...but even so, it would be very wise and prudent to salt your system to 1ppt BEFORE adding the fish.

Good luck 

Erik, you're not the first and you won't be the last.  If any survive, good.  If not, you can catch more later.  I put 60 catfish in my system and promptly killed 58 of them with nitrite.  One year or so later I killed the remaining two and 95 bluegill with a really simple timer setting error.  I'm sorry it happened but what can you do except try to not to repeat it and try to anticipate the next thing that might go wrong  Hang in there and good luck.


How did a bad timer setting kill that many fish?

Ha. When we create an environment that relies on equipment, people and/or power to sustain life, then any number of things even more simple than a timer can end the life of a fish. Mistakes and failures make us smarter, hopefully, and less likely to accidentally kill more in the future. I have killed all the fish I have raised. Some make it to the dinner table, some aren't so lucky, but they all die. Dying is part of living, as they say...

I'd be inclined in your case to leave the fish in the system, and do water changes to moderate nitrite levels to safe levels for fish. The water you remove can be stored aside with aeration, where the nitrite will continue to convert to nitrate, and can be used later as top-up water with no waste.

Erik Phillips said:

How did a bad timer setting kill that many fish?

The intended 10 minutes on, 10 minutes off was instead set to 10 seconds on, 10 minutes off -  in effect no pumping to beds with no backup aeration.  It was 24 hours later during hot weather when I discovered it.  Now, I pump to beds from grid while also aerating from solar/batteries.  

Erik Phillips said:

How did a bad timer setting kill that many fish?
I never thought it would be that easy to kill catfish. I thought they were super survivors I mean they can live in mud for crying out loud!

I know what you mean.  Most of my bluegill survived the nitrite spike.

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