salt may help.. sounds like a fungus
might help with the finrot too,,, but i'm not that familiar with it
i know salting to 3ppt will help the fish, and won't hurt many plants (but would probably kill cukes and strawbs)
if you can, isolate them and try to get them up to 6ppt salt
most "aquarium" meds aren't meant for fish that you plan on eating (there is a warning with pimafix but i'm not familiar with it either... it does say that it's for aquariums only)
here's the pimafix warning:
Warning
This product contains a chemical known to the State of California to cause cancer or birth defects or other reproductive harm. Keep out of reach of children. For aquarium use only. Not for human consumption or for fish intended for human consumption.
take it for what it's worth