Really cool atmosphere. Overall style was fantastic. I was catching Celeste, meets Ecco the dolphin vibes. I really liked the stretchiness of the fish as it swam around the environment.
Feedback: I see people commenting on the controls and movement. I didn't mind that so much, it seemed like you had a feel you were going for. If you kept the controls like this I would give the player more time to play with controls before introducing bigger jumps. I found it frustrating at the first big leap that I had to keep going back and doing that first part over and over again.
Nice work!