Blue flowerhorn face and side turning pink

[Ravens girl]

Hey , I am not sure what's going on. I have a blue flowerhorn in a 75 gallon tank. Water parameters are perfect. 0 amonia, 0 nitrite , like 10-20 nitrate. I feed him a high protein pellet food and once a week frozen brine shrimp or blood worms. Had for like 3 months. He's been really blue and recently got lighter and got more pink around his face and side. I'm just trying to make sure nothing is wrong. 1st pic is like a month ago, 2nd is today. Any advice? Is this normal or could something be wrong and if so what. Thanks so much.

 

[danotaylor]

I’m not a FH keeper, but he looks strong and healthy. If the high protein pellet contains astaxanthanin it could be producing the color change as it enhances color in the red, orange spectrum.
It could also be part of the genetics of you fish and the cooor change is a natural part of its maturing process. If the fish is eating and behaving normally I wouldn’t be too concerned