This was neat! Cute opening and ending scenes and cool general concept.
It was a little awkward figuring out how the game worked, but I got the hang of it pretty quickly. I think it just felt like I was getting eaten/killed and without some kind of visual indication that I had taken over the fish it was easy to assume I had lost, at least for a second or two. But like I said, I figured it out pretty quickly, so not huge a deal.
Overall, this was a very complete-feeling entry with some unique ideas, so great job!