Nice game man! I couldn't understand the speed mechanic at first, but after I checked the symbols below, it just became obvious to me. Only minor inconveniences are that I think the fast fish are way too fast sometimes even if you get the hook right, because of its speed. Maybe it's just my lack of hability, but just saying. That and the fact that the "EXIT" button doesn't seem to work, at least on my computer, are the only bad points I could find. Really nice game, I like the art pretty much. The limitation fits the mechanics of the game, and does not seem to be an afterthought.
Keep on the good work! I really liked it.