Can I treat my whole tank for fin rot even if only two fish have it?

Question

I recently got new fish and I didn't quarantine them. After observing them it appears that 2 have fin rot. Since I've exposed them to my other fish, should/can I just treat the whole tank for fin rot? Or should I treat them in a separate tank?

Answer 1

Get them out of the tank immediately, and put them into a smaller "hospital" tank if you have one.  The best thing to do for fin rot is to keep the water absolutely squeaky clean, and it'll be easier to do this in a smaller tank.  Soak any plants and ornaments in boiled water too, to kill the bacteria.  Clean the water as much as you can in your aquarium to prevent the risk of your other fishes.  Also they should be in a different tank anyway, because if it gets bad enough that they need medicated with an antibiotic, you can't medicate the healthy fish because that'll be bad for *them*.

So yea, I'd say put them in a separate tank right away, and as for your other fish...keep their water extremely clean for the next few weeks to remove the bacteria that's already in there.  Observe them for signs of infection, and don't put the others back in until you see signs of fin regrowth.

EDIT: to your second question...fin rot cannot go away without treatment at all, but by treatment I mean water changes.  It depends on how bad it is.  If most of the fins are still in tact, keeping the water clean and the temperature constant should be enough.  Be careful not to stress them.  But if it's a bad case, you will need medication.  Hope they get well!