As some may know I'm big on flowerhorns,but I've only had one. He's one awesome dude/fish lol,he is probably about 4-5years old. Noticed today his back half is turning black. I'm just wondering if any experts could tell me average life span,and what they think it may be?,had him since he was 1" long.All fish are fine and maybe he is to,I 'm just not sure. Thanks.