Five of my 6 zebra danios were wiped out by a mystery disease that affected only danios. The last one died this weekend. Somehow the sixth danio never got the scourge, and appears healthy and strong. But now he's all alone. I have 5 more danios in another smaller tank. But would it be a risk to move the "exposed" danio in with them? Or, to move the 5 healthy danios into the "death tank" where all the danios died? I'm trying to find the poor lonely little guy some friends but I don't want to put them all at risk! 
