Great concept and amazing colours. Only problem I see is that the tree seems a little sloppy whereas the rest of the design is very, very precise. Try changing the texture on the trunk to be different from the grass and the leaves, too.
The tree and the grass are supposed to be background objects hence the less precise nature of the drawing, it is just supposed to leave the impression while the emphasis is on the fish and cat.
About my design
Simulated process color on black.