I bought a Red Devil almost two months ago. I got him at about 1 and a half inches long, at the very most. The thing is, he hasn't grown at all, atleast as far as I or my room mates could tell. He eats well and poos a ton. o.o
what size tank is he in, growth rate is variable depending on his life conditions and diet. you should be looking for about 1.5" a month
what type of diet is he on?
are you planning on getting a bigger tank for him when he grows?