has the temp gone down? Any other change in water chemistry? Fish will often bleach out when stressed .
where did you come up with that Rob? (18"=3years old?)
i have tilapia at 18" in around 2 years, less than optimal conditions - cool water
where have did you find the info about a 3yr life expectancy? they can live 10-20 years in captivity!
Not sure if this applies to your situation, but my dominate male is white. A larger but subordinate male is more gray in color. Recently the larger male challenged the dominate one and they both were white. So if he otherwise seems health it might just be he is the dominate male.
And that may be part of our problem, also. We don't know what we have when it comes to males and females. We KNOW we have both because they've had babies. We are assuming that at least one of the larger 3 fish is a male - he's a much lighter color and protects his little "cave" on the bottom of the pond - and his eyes are a little bulging - but he was never white like the fish was when I wrote this post. We had thought the other two were female because they were the normal darker color - but maybe that is not the case.