This is such a cute game. The concept is great, the art is great, the exotic fish are great. I made a lot of use abusing the fact that I could jump and place fish beneath me, which didn't feel entirely intended but was fun. I think the mechanic did get repetitive after and awhile and slightly overstayed its welcome, and you could've made the game about 30% shorter (increasing the speed at which you encounter new fish to compensate, of course).
It felt like there should've been some sort of visual effect when you were fishing (Maybe a portal opens up and you cast the line into the portal? or maybe you cast a gravity-less lure off the edge of the screen?), but I'm sure if you'd had more time you would've added something for that.