Got some new orands. quarantine etc..

I bought 3 new oranda goldfish' was not able to resist though they were not 100% healthy, they have whitish stuff on them like slime coat? Currently have them Inside styro box treating with salt and melafix when can I safely add them into my comm tank? Any Advise?

btw these are the new additions, they had whitish growth when in the lfs tank







see anything wrong with them?

this is the styro box

thanks will keep them in quarantine for a month, so far they seem to be doing well. and they look normal.
I think it might have been the water quality in the lfs that affected them

thanks the fish are now in my tank, they are doing well I will try to take pictures later