At FF, each of 6 fish has optimal bait, hook, it is found at one of 4 fishing spots and differs in distance from shore. You need to find 'perfect combination' (which hook and bait to use, where to fish and how many weigh/distance) to catch best fish and score higher.
If you play with Friends Chat, you'll get lots of tips, so you can get fishing best spots right away, that's why this sheet is used - as you can see there is quite some informations to remmeber in 2minutes :p