You see this is quite simple. MOST gator gars will eat their tankmates if they can fit its mouth. But you see if it can'T fit it's mouth it will simply kill it... in the end. I dont give a da*n about that maybe one of youre friends or maybe youre unkle owns a 3' Gator and it lives with Koi, Clarias, Channa's or just ANY other fish. So far so good. ALL tank or pond mates WILL get killed when the gar grows bigger and OLDER. Though the gar is in full size and has not killed anything, he wil get more aggressive and kill his TM's...
This is what happends with 85-100% of all gators. They maybe arent aggressive in Childhood. But as the beast grows older and bigger... you can just find out...