a common pleco gets to be about a foot long full grown. you really should get it out of that tank, it already seems to be too large, and they are big waste producers. And as pcam86 already stated, they are quite powerful
I know they get to be a foot long. And I was either going to return it or when it gets to big for the tank I might be able to get a bigger tank for it.
they like to dig and search in the gravel. I have three right now and they keep my stuff turned up! I had to rescue two from my mom cause she got them not knowing they were gonna get that big and was told that was the ONLY algae eater available. Anyhow, Im giving them to a girl tomorrow who is going to rehosue them in 250 galllon tanks.