Prepare for lash-back!
Whether you use Melafix or not is up to you - some users scream bloody murder and swear it kills labyrinth fish, others have used it without problems. I personally do not believe that API would market a medicine that's actually a fish-killer. They state that they have tested it extensively on all types of fish, including labyrinth fish, and when used as directed, it's fine. I've personally used it with good results, so take that as you will.
You do not need to dilute it. Bettafix is a weaker dilution so that it is easier to measure out appropriate amounts for smaller betta tanks. The end dosage of Bettafix or Melafix ends up the same, as long as the package directions are followed. If you don't have aeration in your tank, you'll want to stir it around gently so that the medication permeates the water instead of sitting in a heavily concentrated clump.
As an observation:
Some people have claimed that their sick fish died after using Bettafix or Melafix. This is a correlation, not a causation. That's like blaming the doctor for your cough after visiting the hospital for the flu...maybe you picked up the cough at the doctor's office, but you were already sick when you went there, and the flu is a respiratory illness. Which means it generally leads to coughing. :-? So, blame the treatment, or the illness?
