Since a rasbora is so small, I would almost be inclined to go buy a little 2 gallon tank to use as a hospital tank until the fish heals. There is a good review in this forum on Melafix that you may want to read. I think it would grow back fairly quickly if the conditions are good.
I definitely think the tetras are your culprits. I don't think adding two more rasboras would help. In fact, adding more tetras may actually help (they may keep their aggression to themselves) but since I'm fairly new to this, I'd wait for a more experienced person to make a recommendation here.
Oh, and my catfish are anything BUT slow moving.

They'd probably be fine.