A not very original concept that brings little to improve on it.
It's rather boring, even with this concept of growing to become stronger. It has no real pull, as I feel no real desire to continue playing it through my single playthrough. The music is rather bland, the sound effects are way too loud and obnoxious, the aesthetics is nothing special, and the gameplay is just dull. In fact, the gameplay feels quite broken in parts.
Sometimes I flat out can't eat a fish, even if I've got my mouth right on top of it. Sometimes I'll end up shocked or poisoned without even touching a fish. And when I even beat the game, the game ended up crashing. At least I assume that's the case, as no ending movie played. I at least hope you bothered to make an ending, and not just make the game freeze when you beat the boss. Also, the controls feel rather floaty; like I have no control over my fish. And that infuriates me.
The boss wasn't even really a boss; it was just a waiting thing until the EAT arrow finally came up. The invisible cloak really makes most of its attacks worthless, and due to that it poses no real threat. Not very exciting at all.
Although not much of a gameplay issue, cheats also appear to not work. I wanted to use one just to get the medal, but I find myself unable to activate them.
Overall, it's a very average game. It works to a degree, but it's unbearably dull; though it doesn't help that the concept of the game is one that really can't have much more variety to it. I will give ya points for trying something different with the evolutions, but in the end the evolutions ended up making it even more dull as it made it easier-and in some cases more frustrating- to play.