Originally Posted by Tree
I had a fish die with melafix. I tried to fix him with all sorts of issues he had when I got him but found out the hard way that melafix does more harm than good. x_x It is all up to you if you wanna use it but this is what happened to mine when I tried to fix his fin rot.
Your fish most likely died from whatever you were trying to save it from - all those issues the fish had. It's funny, no one ever claims that the meds kill their fish when they die during treatment. But if it's Melafix - that definitely killed it, not all the things wrong with the fish.
I've dosed with Melafix at over 4x the recommended dosage without any issue whatsoever.
In such a small tank you would use bettafix, not Melafix. It's a lower concentration to make dosing small tanks easier.
That all being said, I'm not saying that Melafix is a good thing to use. I think there are better ways to treat fin rot, the best being good clean water and time. I agree with the suggestion to get the fish into a bigger tank. I would get a filtered tank that way you can provide a stable environment.