Isolated the GT as he's a punk. So of course the number two fish (devil) decides he's now king and punks on the argentea. I've released the hound and now the GT is back chasing the devil.
It's not been major so far, just chasing but I'm loosing quite a bit of water over the sides.
Maybe I'll try isolating the devil next...or I'll just add in 3 dividers and give everyone a little 18" cube!