Well i have left them in together because over the course of the day the other has deteriorated rapidly and looks like it has exactly the smae thing, not sure of the name of the stuff, ill have a look and tell you tomorrow but it says its for fin rot and fungal infections, they seem a bit more lively, the one that was on the bottom of the tank is near the top now and moving a bit more, hope thats a good sign. I wil;l admit i had a little cry over it earlier, im really upset and feel like this is all my fault but surly they would have had this before we got them as we have only had them a week and it came on really fast