Need a diagnosis please

[Ragtop68rs]

This is my porcupine puffer. He has a big white blotch on his tail and the underside of his stomach is covered in it. I just moved him to quarintine today. He stopped eating last week. I lost my purple tang last week but I didn't see this stuff on it. Any ideas? Thanks

 

[Dmorty217]

Looks to be fungal. the patches are caused by excess skin mucus typically.