Yellow Tangs swimming upside down

[lemadl]

I have a few fish in a 95gallon QT. They are all in the same tank undergoing a 6 week Hypo treatment.

In the QT tank there are 5 Yellow Tangs, 6 damsels, 2 bicolor angles, 2 clownfish, 1 six line wrasse and 1 hippo tang. All are very small fish, hence why they are together. I have quite a few PVC tubes, elbows, etc to provide shelter and hiding places for them.

All are being treated as an Ick precaution.

This morning I awoke to find the yellow tangs swimming erratic (sometimes upside down).

Tank specs
Ph: 8.0
Ammonia 0.25
Nitrite: 0.25
Temp: 80
SG: 1.009
20 gallon sump
fluval 404
2 powerheads for circulation
protein skimmer.

I know the Ammonia and Nitrite parameters are off, I did an immediate 30% water change, and got rid of the Ammonia and Nitrite problem.

What is weird is all the other fish were fine.....just the yellow tangs. Could this nitrite and ammonia problem be the cause of their behaviour, or is this a result of a diffeent ailment?

What is also weird is one of the yellow tangs is perfectly fine.

I do not want to lose them, so please let me know what you think I should do next.

Thank you for your impending advise.

 

[ronjeremy]

did the fish show any signs of disease/problems before you qt'd them???

 

[lemadl]

Yes, they had early signs of Ick. I noticed the ick on the first day and took them down to 1.009 over a 3 day period.

 

[ronjeremy]

are you positivce it was ich, and not marine velvet???

 

[lemadl]

Yes, I m pretty sure, based on the symptoms, white dots on their bodies, scratching,m swimming erratic etc. The Hypo treatment is working on the other fish including the Hippo Tang and the remaining Yellow Tang.

All the others are doing well, so I am completely stompted with what has caused this "new problem".