Cute little precision platformer you got here! As a fan of games like Jump King, I quite liked the challenge this brought and had a good time going through all the levels as fast as I could, getting better at my routes, and admiring all the various obstacles you put in my way to keep things fresh.
One aspect I found very annoying was the controls, however. The biggest annoyance was the fact that, due to how the fish squashes when you charge up, you'd naturally think that the strength of your jump correlates to your charge time in a gradient manner, but bizarrely the jump charge system is binary, where you either flop or do a full-power jump, nothing in-between. It's just so bloody unintuitive! Eventually I learned to accept it and work with it, but in times of trouble, my natural instincts would keep coming back, making me think I can do a half-charge jump and screw me over constantly.
Game was also a bit janky and unrefined. For example, the way slopes/ramps worked was really wonky with how they make you jitter around when you're trying to charge up a jump while sliding, or how they instantly kill your momentum and make you slide downwards immediately when you come into contact with them. Platforming was confusing too where I was never sure if a jump would successfully put me on top of a platform or just barely make it and hit its side. Level design was really haphazard at times too and didn't achieve a smooth difficulty curve and sense of progression.
Also, there were a lot of aspects that felt a bit underwhelming: for example, I was disappointed that there was no good/bad ending depending on your performance considering how strongly they imply it at the start, but then again, I was confused as to why the game was displaying my total time at the end instead of adding together my best level times, which would seem more natural.
Despite its roughness, which I suppose is to be expected for a jam game, I still had a decent time with this and was compelled to keep going just because of how charming it was, so well done for the most part.