It's not bad, but it's nothing risky either. All the concepts and ideas in this game are either done already or just playing it too safe. There's not really anything fresh or interesting keeping me invested. When you make a game, you should always ask yourself "What's the point of this? What's the player getting out of playing the whole game?" In this, you eat fish, you get points, and you go on to the next level. That alone isn't gonna make people want to keep playing because they KNOW what's going to happen. For example, let's say you offer upgrades. The more fish you eat, the more points you get, and you can spend those points to make the shark's teeth bigger so he can do more damage or bigger fins so he can swim faster. That's interesting! Seeing your character slowly evolve into a bigger, more awesome version of themselves because you played the game well is incredibly satisfying and will definitely make people want to keep playing. It gives people a sense of progress and accomplishment. A reward system is a good way of keeping players invested.
Next, while story isn't a major part of these kinds of games, atmosphere is. No offence at all, but this looks like the kind of flash game you'd see on a little kid's website. I'm not calling you a child, it's just that this is what I get from the atmosphere. Now while the artstyle has a childish vibe to it, it's not what bugs me. That's an artstyle choice, and it looks fine, cute even. But the music is what grates on me. It's overly simple, there's not really anything catchy or interesting about it, and it's muffled. It's certainly not something you'd listen to on your ipod. Now, it doesn't have to be amazing music, but it should at least be somewhat pleasant to listen to. It should be clear, simple yet catchy, and give the right feeling. If you want the gamer to feel happy, make it upbeat and cheerful. If you want them to feel sad, make it slow and deep. Atmosphere REALLY makes an impact on a game, and it shouldn't be taken lightly.
As a whole, it's not a bad game. But it doesn't hook me either. I played a few levels, said "okay, this is alright" then got kinda bored. Now, I know this sounds harsh, but you're not a bad game designer. I'm just trying to help point out the flaws so that hopefully you can use this to improve your stuff later. Anyway, that's all I have to say. I hope you continue to make more games, and I wish you the best of luck good friend.