Good foundation, really nice graphics and good humour.
I found it to be quite repetitive and grindy at times, nothing new was introduced in later areas other than bigger fish and different upgrade text. It was also annoying when you went for the deepest fish and there happened to be none there at the time so you got nothing from the cast.
One suggestion I have is making less small fish and more large fish as you cast further, which will help the lack of benefit I found at all for going for the perfect casts.
Hope this is helpful