Yo this game is sick! The controls are responsive, hitting enemies feels punchy and I love the way the fork bounces around!
As far as criticism goes, I think it would be more appropriate for the bigger fish to take 2 hits to kill instead of the small ones, since they are easier to hit and it's more intuitive.
Also I felt like the tracking of the turtle boss makes it hit you in unfair ways, because it makes you run in circles. Since there are bullets coming from above, people will try to stay at the bottom as much as possible, but because the turtle tracks you, the player will have to inevitably go up. The RNG of the bullets will determine whether you get hit or not, since it is unreasonable do dodge all of them precisely in a short amount of time.
You've done a great job with this demo and I hope you'll keep developing games in the future :)!