Great looking kid nice shot nice composition... nice repeating verticle lines in the fish, and on the stringer
I like the pattern of the fish and the hooks. Only thing is that I would try to eliminate the harsh shadows on the boy's face.
I like the idea of the photo, but using your onboard flash really takes away from what a great photo it could be. If you need the flash just because of lighting situations and a tripod is not handy, try holding a piece of white paper in front of your flash to reduce the harsh lighting.