Fungus

[mullinsd2]

My clown has developed a small cotton like ball on one of his bottom fins what is this and how do I treat it. I think it's a fungus. R my other fish in danger?

 

[Crazy4Coral]

It could be Ich but a pic would be nice.

 

[MarinaP]

Most probably lymphocystis. Improved water parameters will help to clear that up.

Fungus is quite rare in marine fish.