Thats about the going rate for farm bred cichla. Most likely a hybrid of monoculus/ocellaris. Growth is quick a inch or so a month isn't uncommon given good water conditions and a steady diet. Small cichla can be fed multiple times a day as well, their metabolism is quite high. Don't be afraid to keep their water temperature high either, 85f is a good place but be sure you provide a lot of water surface disturbance (power filter, air pumps) because high temp=less oxygen but the higher temp cuts down on ich, another thing small cichla are prone to getting. Hope this helps, welcome