Use the left mouse button for melee attack and right mouse button for a ranged attack; and collect all the dead fish in your boat!
But hey, sorry this game isn't finished and such, I was kind of in a rush. I even forgot to add the sound and music that my partner made! But if you are interested in playing the music while you hunt for fish anyway, here's a link to the music: https://soundcloud.com/haxen-2/the-endless-hunt