Interesting fish the Heron caught, I think the Heron is a bit soft with the two light gray trees in the backround competing stongly with your center of interest
I normally don't like busy BGs but here it works for me. As mentioned, the bird looks quite soft and I would put him further to the right in the frame to give him room to 'fly into'. I also wish the wings were higher up or down. Keep them coming!
I don't mind the greenery and small twigs in the BG, but I agree with DMills about the two trees competing for attention against your subject. Too bad there is one directly behind. As posted the image quality suffers from resizing compression and/or heavy cropping. Great catch by the heron, and from what we see here this looks like a great location to go back to!