[SnailShellBoatman]

So one of my bloodfin tetras as a serious problem, mainly in the area of the back fin. I first noticed that his tail was badly damaged a couple days ago and I figured my golden gourami was the culprit. I separated him from the gourami but the tail only seems to be getting worse. In fact the back fin is almost completely gone! I've since moved him to an isolated sick tank where the Melafix can really sink in. Can anyone tell me if this is tail rot or simply a natural reaction to a badly nipped tail?

 

[SeaHorse]

Now that you've given some more "restful" space, and meds to counter any infection, IMO that could grow back. I've seem both... some recover fine, other's don't make it.
Keep us posted!