I'm having a problem with my fish. They are all dying for some reason, I cleaned there tank a week ago. I bought two new gaurmis and the other gaurami I had before both of them started to fight with the other two. So they both died and then my old gaurami its skin was tearing apart. Then my sucker fish and swordtail died. Then today two other fish died I don't know what's wrong. The water temperature is normal. I put some Melafix on the gaurami. Will that hurt the other fishes. So is there a way I could save the other 5 fish I have left. I have another fish tank should I put them in there?

Do you use Tap water?

Yeah but then I add aqua safe to it which is a conditioner for fresh water aquariums.

You add melafix to the water, not directly on fish. Never change more than 10-25% of the total water. What size tank and how much water did you change?