Pretty impressive! I loved the music and art, and the controls/info page had an old-school feel like TMNT that really got the nostalgia going. Honestly this was the first game from the jam I played because I thought the cover/title art was cool.
I don't know if you meant for it, because pressing [spacebar] moves you through the tutorial scenes quickly, but it also pulls you out of the game and back to the title menu.
The first time I turned back into a little fish I had no idea what was happening, even though I read the tutorial page. Once I figured it out though, that was a pretty cool mechanic.
I would have liked the bullets to go more towards where the mouse pointer was than at those angles, but that's pretty understandable. I did think that you probably shoot too many bullets at once though, because once I got to the boss I shot him so fast he never moved or did anything before dying.