if my other tanks aren’t adequate, what should I get to make it work? Also, how long would the tank have to be fallow?Tough to say, I can’t clearly see any blanching that would indicate the presence of crustacean parasites. The issue could be flukes, leeches or turbellarian worms. You could try prazi - that would help against flukes. Leeches or turbellarians would require a formalin dip and then moving the fish to a new, parasite free tank, to allow any parasites in the tank to die from lack of a host.