Guppy has a bitten fin

Question
Hi, my guppy is missing a large part (almost all) of his tail and appears to have a lot of trouble swimming. I was wondering what I could do to help him. He was bitten by another male guppy but I have separated them. The two of them were alone in a 35 gallon tank with plenty of hiding spaces. I don't know what to do but I know that I couldn't kill my guppy.

Answer
Hi Allie,
Poor little guy.  You will have to treat him with an antibiotic.  Kanamycin is very good, but hard to find.  Tetracycline, or Furan 2 are also good.  You could also combine Maracyn, and Maracyn 2.  He must be treated.  Follow the directions on the package, be careful not to overdose.   Keep your water very clean, free of ammonia, and nitrates.  Check for ammonia before your treat.  It is important that the ammonia in your tank is down to zero, or safe.  If you do have ammonia, make water changes until you are rid of it.  This is very important, as ammonia is the number one killer of fish.
Hope the little guy recovers.
Lynda