platys, mollys, mickey mouse,and gouramis

Question
I have had my tank for about 3 months, and I have recently found that my fish look kinda sick. I've had 3 die so far. My female guppy had babies, and to my surprise they are as healthy as ever, the older fish are the ones whom are sick.My new silver female platy has a type of fuzzy stuff around her mouth and she's not eating, mmy gourami's (I have two male) their scales are looking pretty weird like their chipping off, or shedding in some way. I also have treated them 3x's with natural fiah parasite treatment.I change their water every 2 1/2 wks. I also have tried not to add the fish too quickly, so not to upset the enviroment. I'm trying hard to save my fish, Please help. I appreciate your time thank you.

Answer
It sounds as though our paty had a fungal infection and you can buy treatment for that.

I knwo about the babies, my tank had a massive failure and all the fish died except the guppy fry amazingly, there strong lil fishyy's.

How big is your tank as that could explain some things and what type of gourami's and any other fish? as they may be fighting