I have a 7" jag a 10" & 12" oscar and 7" GT in a 125 right now. When i got the jag he was about 5" and the gt was already 7" but hes growing so damn fast hes just now starting to terrorize my green terror (no pun intended lol) I have been keeping an eye on him lately I may have to get rid of the GT soon so he wont be killed. as with my oscars , they usually test eachother out but never really do anything just alot of taunting back and fourth then one swims away. Jags are the **** though, one of my fav fish, but we'll see when that jag becomes monsterous , may have to upgrade cuz im NOT getting rid of him or my oscars lol