I love the game! It's very creative with it's idea and it works great with the jam's theme!
All of the battles are very different and really fun to figure out, and the fish feels great to control! Also, the art look really nice!
The only complaints I'd have with it would be that the trash cleanup can feel a bit tedious, with how much trash you have to move back and forth (especially after how tense the battles are) and also that it feels like it could be possible to trap trash in the corners around the pipe, which would blow if you just defeated a monster and couldn't progress any more.
(Also, an in-game tutorial would be nice, as it's not very intuitive that the pipe would remove the trash)
Other than that, this is an outstanding game and I really enjoyed playing it, awesome work!