That is one ambitious KF! Nice and sharp in the eyes, wish the fish' eye was a little sharper, maybe you can do a selective sharpening.
There is a bit of noise in the BG and something glowing in the feet.
Nice detail in the plumage. Did you take many or did he go away fast?
That's a pretty good sized fish for that little bird! I like the placement of the bird in the center of the frame because of both the perch and the fact that it's staring right at you. I'd like to see a little more DOF. I'm not sure what aperture you were using; it'd help if you'd post complete tech specs on your photos. As Fabs pointed out, selective sharpening may help.
Excuse me ,I forgot to put this information
Tv( Shutter Speed ) 1/320
Av( Aperture Value ) 5.6
ISO Speed 640
The fish's eye is on the edge of the focus line. There is no serious post processing.Just levels correction and general unsharp mask.I forgot to reduce noise in BG too.