in my short experience on arapaima, this is what i can say.
i bought mine on a LFS and its other sibling was left there. i bought it at about 4in in length. after a month, my paima grew to 8in. i visited his sibling and saw it only grew an inch or so. i guess they were under feeding it.
when they were both on the LFS, their color were golden green. after a month, mine became copper green with dark tinges all over. the one left in the store was very dark and almost black in color.
conclusion: when a paima is fed and is not stunted, it should be lighter in color. the space in the middle of its scale gives dark hue on it. when its stunted, the scales wont grow larger. hence, it would be darker. if healthy and fed adequately or power fed, the scales will grow much larger. out coloring the dark inter-scale coloring.
but its just from a newbie on arapaima care. hope it helps and i hope it also made sense.
