Fable Anniversary Fishing Lessons represents an important side quest and it is recommended to start it as soon as Fisher Creek area becomes available.
The quest is simple, but you should start it right away, because you receive your first fishing rod and you learn how to fish.
The following Fable Anniversary walkthrough describes how to do the side quest and the best fishing location for the quest.
Trophy: Golden Fish
When you access Fisher Creek for the first time you trigger a cutscene in which wasps attack the resident of the area. Rescue him from by killing the wasps and he will give you a Fishing Rod.
After that he teaches you how to fish. Stand on the pier next to the ripple and press the button when the icon flashes a fishing hook. Wait until you feel a bite and press A to reel in the fish.
Repeatedly press A until the fish icon reaches the left side of the bar, but only reel in when the fish is not pulling away or you may snap the line (watch the color of the bar turning from green to red).
Keep fishing until you catch your first fish, a Golden Fish, which is also a trophy that can be used to get more renown. The quest ends here, but you should keep in mind that if you leave the area without catching the fish you wont be able to complete the quest.
Fishing is very important in Fable Anniversary, because it provides an unlimited source of food, but most importantly it can be used to collect Silver Keys or hidden items.