What size is your tank? They get to a pretty good size I believe. I have one (2-3inches) currently in a 20 Long, but I plan on getting a bigger one for him.
I did have two. Don't feed a 2-3inch peacock a 2-4 inch red worm. I think the poor guy choked on him. Thats a mistake I won't make twice. Felt so bad afterwards.
My other one is doing really well in my community tank. I'm no expert on peacocks, but I like 'em.