New to me disease

[mtnmonster]

These fish were placed in an already established and healthy aquarium after I moved the previous inhabitants.  I didn't start the med trio because there was no signs of disease in the lfs tanks nor mine. 5 days into keeping these fish in quarantine I had a guppy disappear I found him dead being eaten by snails. I immediately checked the other fish and sure enough found one of the platy with white lips. I immediately added a dose of parallels, maracyn, and ich x. 

Water parameters are:

79F

Nitrate 20ppm

Nitrite 0

Ammonia 0

GH 150ppm

Kh 180ppm 

PH 8.0

Here's a picture of the only fish showing signs of disease.  None of them showed any signs yesterday.  

[ange]

White growth is generally an indicator of fungal infection. Some bacterial infections like columnaris can also lead to white around the mouth. I would suggest a course of Maracyn for the survivors, especially since fungal infections often cause secondary bacterial infection after the fish is compromised. Best of luck with your treatment.

[quikv6]

That does not look fungal. To me, that is Columnaris, shown as the start of mouth rot. I have had a few cases of it, and they were all with Platys as well. I actually have one fish that I treated a year ago. He started off just like yours. Rot set in very fast. Thankfully, I was able to treat it, but he lost have of his upper mouth in the process. He is deformed, and can only eat certain foods successfully.

Maracyn will most likely not be effective for Columnaris. You have a few options:

1) Kanaplex + Furan 2. (Furan 2 is hard to find nowadays...Jungle Fungus Fizz tabs are a good substitute.)

2) API Triple Sulfa (Also hard to find)

3) Maracyn 2.

I have successfully used option 1 and 2, on different occasions. I have tried Option 3, but wasn't successful with it. Mouth rot can spread fast. It's not like fin rot....as it may not grow back.