Help! My angle is declining rapidly

[psott]

Long story short. I got a steal of a deal on a tank with fish that I currently have in a temporary tank in water from the original setup as I move and replumb the setup.

2 days ago I noticed some fin deterioration on the angle and when I tested the water its at like 200 nitrates! Yikes.
I did a 30% water change, all the RO water I had onhand and started dosing NoPox to help bring it down.
This morning it has gotten considerably worse and now he seems to not be eating. The other fish seem to be eating okay with maybe some signs of slight fin deterioration
I'm heading out to get some KanaPlex now but any advise is appreciated!

Thanks!

 

[vetteguy53081]

Any other fish in with it? Looks like nipping and may be due to a smaller tank.
I see also what looks like dots, possibly inch but don’t assume it is. Would need clearer pics to confirm
Assure your readings for ammonia, ph, salinity and nitrate are within safe range
Ammonia- < .03
Nitrate < 10
Salinity- 1,024-1.025
Ph. 8.1-8.3
Temp 77-79
Add oxygen via air stone

 

[psott]

Yes, its in a tank with blue tang, yellow tang, foxface, clown and wrasse, very over crowded, but they have been together for a few years and don't seem to fight.

So Apparently any sort of antibiotic is only available from a vet here now... so the best medication I can find is Kordon Rapid cure. Its a malachite green based medication. Its not reef / live rock safe.

The water parameters are still awful; about 150 nitrates, water change and nopox barley made a dent.
Salinity is low at 1.017 which is what they have been in for years is my impression.
Temp 77.

My thoughts right now are to make as much fresh salt water as I can and move them to the permanent tank (probably half full) and treat with the Kordon Rapid cure and then in 3 or 4 days run carbon to remove the medication. I assume at that point I could safely add the live rock.

What are peoples thoughts on this?

Also should I make new salt water closer to what they are used to and slowly increase salinity or make it to 1.024
And in terms of acclimation to the new tank what are fish most sensitive to? temperature?