Yes, Heavy weeds contribute to the Dark Green back & Yellow belly. I fish a lake in East Texas with alot of Hydrilla and just about all the bass I catch around or over the Hydrilla beds are the same color from there. The water is also a tanic color which I think contributes as well.
thanks for answering, it's interesting, in Europe the pike, at the end of season, live in weed and have the mouth blue/green because of the weed but the color of body do not change