I went back and looked at the date on the first time I posted his picture it was january of this year. He's about 8". His diet is high protein. Mostly fresh raw shrimp and scallops supplemented with pellet, worms, and grubs. I use a color enhancing supplement that I purchased from Jehmco.
I think the growth rate varies greatly with the size of the tank, water changes and diet. And in particular after seeing this guy against his siblings (heretofore called "lunch") I would say the individual fish. I have nine other Managuense right now and have had many over the years. This one is the nicest when it comes to pattern and color.