I have 4 black Molly's in a 20g. Yesterday my female betta was acting strange and this morning she was dead, don't know what happened. This morning I also noticed white spots on all my black Molly's. The white string thing coming off of her is an anchor worm. I'm treating the whole tank for anchor worms and tonight will be my third treatment with parasite guard. Perimeters are normal and unchanged, 0 ammo, 0 trite, roughly 20 nitrate. I read that black Molly's are brackish water fish but I have them in a freshwater tank (untrained LPS employees ) could this be the cause? Is it fungus?