I have had a Tomini tang for almost a year. He was 3 or so inches when I got him, and he's supposed to grow to 6-7 inches. He doesn't seem to have grown at all, but he eats like a pig, lol! If your baby tang is really very small, you could possibly have some time to see him grow out of your tank. Until then, you have plenty of time to fall in love with him enough to mandate a new, larger system just so you can keep your baby as he grows!