He's 2" long, and hes going om-nom-nom on mosquito larvae and convicts

From what I've gathered, they grow up to 12", are hard to get off of live food, and prefer to be in groups. This was the only one there though, should I be looking for another or will it be fine alone?
He's in a 20 long for now, when he gets big enough I can put him in a larger tank.
When would be a good time to ween him off of live foods?

From what I've gathered, they grow up to 12", are hard to get off of live food, and prefer to be in groups. This was the only one there though, should I be looking for another or will it be fine alone?
He's in a 20 long for now, when he gets big enough I can put him in a larger tank.
When would be a good time to ween him off of live foods?