@dbjunkie Id say probably our ATFs are similar size. My VATF still punks the Gatf around though he has his moments where he rips on the VATf as well. I Don't think mine are really all that aggressive to other species but only to themselves. When I had my Arowana in there, they'd all get a whooping... I dont know if I've seen really large tanzies around but I'm sure I've seen small to medium sized ones. The long slope of their jaws/face is unmistakeable. I have never owned one so I cannot comment on their behavior or aggressiveness in comparison. I'm sure he'd put on some size in a bigger foot print. Maybe it's time you put in a xlarge dither that can soak up aggression. Like a tarpon or perch, maybe peacock bass etc.

