Also, and this is strictly from my own personal experience, all of the wild-caught fish I've owned and raised have always been more shy than any of the tank-raised fish I've had. This may seem fairly obvious, as the fish aren't used to being in a box with people staring in at them.
It can also be that if the tank is in a low-traffic area, the fish just isn't used to people. Putting in some facetime and sitting in front of the tank for a while each day could also help him warm up to people a bit more.
Getting them to hand-feed can also help him feel more at home and counteract his shy demeanor.