they all look that colour when big. dark on the bottom half, grey/brownish on the top half of the body.
red belly or black, it doesn't matter. when they get about 18" and up, they all look pretty much the same, no matter what species of pacu.
red belly or black, it doesn't matter. when they get about 18" and up, they all look pretty much the same, no matter what species of pacu.