Goopy white stuff on molly!!! Please help

[Bettaluv]

So, I was looking at my fish today, and I noticed my silver lyretail molly had a lot of goopy white stuff on his tail. It is not like small little white stuff, but like little bits of half-dried glue that is squishy. I don't think it is body fungus either. I just introduced a new fish, but that new fish was quarantined before introduced to the tank, and that fish is showing no symptoms! I am really worried because i have three mollies in there, and I have no idea how to treat this/what it is?!

 

[pocket22]

Pic, plz?

 

[Bettaluv]

I cant get a good one, sorry, but on further examination I suppose it does look sort of fuzzy...

 

[Bettaluv]

so after a while, it looked as though it was getting better. Now all three molies have the "stuff" on them. They are all lying on the bottom of the tank, and they looked dead, but they are still alive. They have little to no interest in food, and I am worried that they are starving to death. I have heard of something called Columnaris, but I dont know if that is it/how to treat it.

 

[butterfly_koi]

Are the fins ripped/frayed in any way?

 

[Bettaluv]

Are the fins ripped/frayed in any way?

No, not that I can see at least.