I'm new to this forum... I hope I'm doing this right. I received this tetra 2 months ago from a friend, it was in a tank with an aggressive fish, now it has a white spot on its tail fin and I have treated it with Seachem paraguard for 3 weeks. The spot has disappeared before but now it is back. My other fish do not have any spots at all. This tetra is being picked on by another fish (an angelfish) that also came from the friend. It shares a 55 gallon tank with 1 angelfish, 4 corys, 5 otos, 3 snails, and 7 mollies in a planted aquarium. I'm thinking about putting the tetra and mollies in a ten gallon aquarium because of the angelfish. Is the one spot fungus? Is it contagious?