OP, like JayC74 said, try it first but keep an eye on them.
I initially had 3x IT's at roughly same sizes (+/- 1"-2" from each other), 8"-11" at the time. Then two smaller ones ganged up and apparently stressed then killed the alpha, my best looking IT. I still blame myself for not separating the alpha before it was too late. Now that was about a year ago or so. So I ended up with two smaller IT's and they have been living together since, and now they're at 10.5" and 11.5". Granted that I have a couple of bala sharks and a feisty leporinus in there to help breaking up any fights, although I rarely see them fight. They both don't eat the same pellets, one eats floating and the other prefers sinking, which may help too.
I admit that when I'm away from home for more than a week, I always have a divider up them as I still don't trust them completely, just yet.
Try your experience and let us know.
I initially had 3x IT's at roughly same sizes (+/- 1"-2" from each other), 8"-11" at the time. Then two smaller ones ganged up and apparently stressed then killed the alpha, my best looking IT. I still blame myself for not separating the alpha before it was too late. Now that was about a year ago or so. So I ended up with two smaller IT's and they have been living together since, and now they're at 10.5" and 11.5". Granted that I have a couple of bala sharks and a feisty leporinus in there to help breaking up any fights, although I rarely see them fight. They both don't eat the same pellets, one eats floating and the other prefers sinking, which may help too.
I admit that when I'm away from home for more than a week, I always have a divider up them as I still don't trust them completely, just yet.
Try your experience and let us know.