Good idea! You implemented this rather well.
I quite liked the concept and general gameplay. Good music as well :)
I would have liked it if the tongue was faster, that way it would feel safer to use. Right now it feels like it's only safe to use the tongue if you happen to have upwards momentum.
Another thing I liked was the fancy art! The backgrounds are very nice.
I managed to get to the level with the water and fish before stopping, you did good on this project! Fun idea, good execution :D