I really love all the color used in this image. Somehow you managed to keep them very natural looking and still seem bright and cheerful. Regarding color, I think some in the sky would have been nice, even if just a light blue or gray to give it some feeling.

I absolutely love the effect of the water. It's very difficult to draw and you got a very realistic feeling with the soft rippling waves; kudos!

Another thing I love is the fish! A lot of people don't take the time to actually look at things before they draw them, and you got the fins all right! I love the speckled design you gave his skin as well, makes him look very realistic.

The only thing I think could use some work would be the anatomy. I know that you're going for a stylized look here, but their hands still seem very awkward. The one that's holding up the fishing line looks more like he's holding up a dirty sock. If you've ever gone fishing than you probably know that fish are fairly heavy and when you're holding the line you have to grip the whole thing because those fish will be wiggling and flipping and bouncing around. The females hands also seem very small though that isn't quite as noticeable.

Overall, a good job and a very unique look to a bright colorful picture.