I have a 29g with a single male convict. He is my mini-monster. If he turns out to be one of those freakish convicts that get really big, I can always move him up into my 210g.
I wanted attitude in a small package and he is it. Not afraid of anything and very personable. Does not hide at all and is super owner responsive. I might consider a female for him if I could find one as nice as him. This little guy has beautiful fins and trailers. Convicts in my area are a dime a dozen, everyone seems to have them. The only issue are most are butt ugly, so I almost feel like it would be worth breeding some nice looking ones.