Can you see the bonefish in the picture? It's amazing to me how these fish can adapt to their surroundings.
The bonefish in the Florida Keys have dark very modeled colored backs to help them blend in to the dark turtle grass bottoms while the bones in the Bahamas (like the one in the picture above) live on light sand colored flats and have light colored backs.
Some bones have a light grey look to them with the right light. That's why we call them "the Grey Ghosts of the flats". Many times all you can see from a distance is the shadow that they cast from the sun above.
I took this picture of this bonefish that is full bodied front and center in the photo when the fish was at my feet. Imagine trying to see this fish quickly at 50 ft moving left to right. This is one of the many reasons why bonefish are one of the most exciting game fish to target with a fly rod.