Thanks a lot for giving such thoughtful feedback! The controls are definitely unnecessarily complicated, especially when movement is a main focus of this game. We will simplify it for future iterations.
As for the fishes dancing to the music, it was a happy coincidence in that their movement cycles is around twice as fast as the music beat, so it often randomly syncs up with the music. I'm glad it worked out!
Great feedback about the Gameboy aesthetics. As I worked on this game I slowly noticed that scaling and rotation aren't great for such a low resolution since the result will be blurred and hard to see. Will definitely keep this in mind for the next GBJam :)