I liked the first and second stage but the third stage has all difficulty crammed into the beginning. The "spit" is not intuitive to use since there's no indication of when it's up and it's not barely enough of a deterrent for the predators. To fix this, I would suggest making the spitballs easier to hit, or adjusting the zoom to make the rabbits easier to hit. The predators become increasingly more aggressive which makes it feel like you can not make meaningful progress. Perhaps a bigger grace period after getting "killed" would lessen the issue. I'm a bit overly negative here, but I do feel like it has great potential, with the evolution of the game and player being a satisfying progression.
Also, I liked the aesthetics. Just make the small blue fish have a different color than the background to make them stand out from the background more.