Guppies Losing Color

[GetItSahn]

I had 6 guppies, 2 mollies, snails, shrimp, and three cories in my tank. I went to buy 2 more female guppies a few days ago. One died last night. It started when they lost color from their tail. From the end of the tail to the base of it started to turn white then became transparent over the course of 2 days. I have my one guppy in 1 gallon tank atm just incase this is contagious or i need medicine. Her tail started to turn white this morning. Other symptoms are they become very lethargic, anti-social, and the one who died kept nosediving into the substrate like she couldn't swim. The faster I get a response the faster i can treat her or move her back to the main tank.
 
All info is appreciated. Any questions just ask. ( My water parameters are fine, just had them checked when i went to the store)

 

[Blondielovesfish]

It sounds like it MIGHT be fin/tail rot.
I'll wait for an expert to come along though as I don't know a lot about guppies

 

[GetItSahn]

It sounds like it MIGHT be fin/tail rot.
I'll wait for an expert to come along though as I don't know a lot about guppies

That's what i told the lady at PetSmart but she said it's not. I think it's fin rot as well. I didn't think fin rot was this deadly

 

[Ninjouzata]

Is there any chance you could get some pictures? 

 

[GetItSahn]

Is there any chance you could get some pictures? 

sorry no, it's exactly what i said it is though