Nitrite after medicating

[migston]

I was on week two of Quarantining my Banggai Cardinal and after hearing of so many of em dying from internal parasites, I decided to do a prophylactic treatment. I got some product called Paragon which was recommended by my LFS. I followed the instructions and dosed accordingly.
The Banggai did fine, he was acting normal and eating. This went on for five days. I was about to put in the third and last dose when I decided to do some water tests. I found Nitrite reading off the scale! I freaked out and since the Banggai had been in QT for three weeks already, I went ahead and got him out of there and into the DT. He's doing fine.
My first thought was that the medicine wiped out my nitrifying bacteria but when I did an ammonia test, it read 0.
Could it be possible that something in the medicine reacted with the nitrite test reagents resulting in a false positive reading? I did a 50% water change and ran carbon to get the medicine out. It's been a few days now and the reading is the same.
Anyone know what happened? How can I make my QT safe for my next fish? I did another 50% water change and will test again tomorrow.

 

[beth]

Originally posted by migston
My first thought was that the medicine wiped out my nitrifying bacteria but when I did an ammonia test, it read 0.

You hit here with this observation. The biofilter is good enough at processing ammonia but doesn't quit make it completing the cycle, thus you see the nitrites.
The only prophylactic treatment that you can opt to do in a QT is hyposalinity. All other treatments will result in degrading the biofilter. Thus, you only want to perform medication therapy when necessary. And, then, keep close eye on your water quality.

 

[migston]

Ok thanks Beth. Up to now, the Nitrite is still off the scale even after another 50% water change. Hard to believe that this much nitrite built up after just 5 days, but I guess I'll wait for it to cycle once again.

 

[beth]

If you have fish in that tank, you will need to keep doing water changes to get those nitrites down. Add some subtrate from your display in to the QT.

 

[migston]

Luckily I had the fish in the QT for about two and a half weeks already when I started dosing the Paragon. It stayed in there another five days when I did the test. So since the three week quarantine to check for ich was over, I moved him to the DT. He's been doing well and actively hunts at night.
So I'm not worried about my current fish. I'm just annoyed that I have to go through another cycle. Did another test last night and it's still off the scale. Again, no Ammonia though.

 

[beth]

Oh, ok, that's good then. My pajama cardinal [kissing cousin to the Banggai] is out and about too after lights go off. He is difficult to feed. The only thing he nips at just a tad is brine. I'm assuming he is eating pods produced by my tank. :thinking:
Here he is!

 

[migston]

Wow that's a beautiful fish Beth!
How long have you had him? Do you think it'd be possible to get them to eat at the same time the other fishes do? I'm trying to build up my pod population, but it's tough with a sixline wrasse in the tank.

 

[beth]

These guys eat a dusk and dawn. So for tank life, when lights go out or just before they come on [and there is still lights in the room]. Just nature. Bang Guy breeds Banggais, so you might want to ask him for advise.