Guessing a fish's weight -
If you reel in a fish and it comes in very easy without line tension it
will be a small one. If it is an average size fish the tension bar remains at yellow for a long period of time. If it is a large fish the tension bar will go red, do not reel it in immediately, you have to tire the fish by doing circular motions with the analog stick as you reel it in.

Bonus lures -
To unlock additional lures select tournament mode and catch the
largest fish of the day.