If you are referring to Aequidens metae -
I have a group of four. I got them from Jeff Rapps in November. They grew very fast for a medium sized fish. They are active and not shy. Curious about most things, but not overly aggressive to other fish. They are quite aggressive with one another however, and I've found that any conspecifics are also treated with aggression. My largest male metae which is now about 4.5 inches killed one of my Krobia xinguensis, and nearly killed another. They have been extremely hardy and great eaters. They will gobble up just about anything I put in the tank.
I'm not sure how one would do with a GT. I would be hesitant to try it because they are so closely related. They might see each other as a threat and fight quite a bit. If you have other options, I'd explore them. If you want to gamble, nothing smaller than a 75g.