I got mine at close to 11 inches back in August and I would estimate only a coluple of inches of growth in length since then. He has gotten a lot fatter though, surprising since he never seems to eat.
I think that happens to most fish actually. Most fish's growth slows at a certain length, mainly when they're large enough or at least have an average adult length.
i think it depends on the individual, i had 3, one is about 1/4 bigger than the other two and have twice the girth... and it just so happens the to smaller ones have some real intense colouring, not so much the big fella
