A couple days ago, out of the blue, I lost one of my balloon mollies. He was having a hard time swimming, so I thought it was swim bladder disease.
Today, however, my one remaining neon is white and fuzzy

and the rest of the community is acting very sluggish and out of character. They're not excited about food, either.
Nothing new has gone into the tank, so I have no idea what the heck is happening. I thought ich was spread through contact - perhaps the neon doesn't have ich? What else is white and fuzzy?