I really liked the theming, the music, and how each sea creature spawned bullets in a creative way that felt logic.
Several things annoyed me, however. The hitbox of enemies and bullets often didn't seem to match their size, the dash felt a bit weird to angle. I would either make the enemy hitboxes bigger, or increase the speed of your own bullets so that enemies are less frustrating to hit.
The ammo replenishing works well, I think it could use some tweaks to make the game flow better. For instance, during the boss battle it's wait a bunch of seconds while doing basic evasion, catch the blue bullet wave, repeat the waiting. Maybe having ways to replenish your ammo through risk could help ease the waiting (dashing through red bullets for instance, or staying close to red bullets for long periods of time).