I am a huge fan of the artwork, I think you guys did a really great job regarding that! But gameplay wise it leaves a lot to be desired. The game is neither challenging, nor gives the player any incentive to keep playing for more than a minute. I think an easy way you could solve this issue is by giving the player only a limited amount of ammo and a certain score they have to beat in a set amount of time, if each fish were to give the player a different score, there would be actual strategy involved in throwing your dynamite. But the way it is right now, I unfortunately did not enjoy playing it very much.
I think the idea is silly and has a lot of potential though :)