what species is he? there are many things that accumulate to a fishes growth. Like: water condition, tank mates, diet, tank size..... do you know what he is? any pics?
i think when my kelb turns up i might have to put it on a live diet to catchup the rest of the 'pack'. i noticed a difference in growth between pellets and live - live much faster growth...but a lot more expensive, unless you breed your own.
Growth rate differs from fish to fish, lots of food on demand, tank size and at least weekly waterchange will help speed up growth. Prob 6 months to a year at least to get to a foot long depending on tank size, then they will start to thicken up which takes longer- hard to put a time frame on it though
Avoid live and save ton's of cash, and have healthy fish, he will be fine with Hikari Bio-Gold Pellets, and his coloring will pop. If there eating pellets, you should be jumping for JOY, theres Bass owners on this site, that would do anything to get there cichla to eat pellets.