It's not a bad entry at all, but I think it could use some balancing. I think making the projectiles go further would fix it, since you experience a lot of near death experiences when you kill larger fish. Another minor complaint I have is the diving speed, which I feel like is a bit too slow. Maybe increase the fast diving speed.
Visually though, it is simple but it works consistently, but I feel like it's missing particle effects (for example either when you kill the fish or get killed)