I believe one of my fish or rays may have an internal parasite. I do not know who but, this morning I saw a long stringy, white/ clear poop floating in the tank. I have a silver arowana, 2 peacock bass and three motoro stingrays. I have never fed them live while they have been under my care the exception of earthworms when I first obtained the rays. they are currently eating frozen shrimp and tilapia. what would be my best course of treatment? thanks.