To fish, first equip a fishing rod and bait in the ranged and ammo slots. Then, find a body of water, place the player character at the edge, and type /fish, or choose Fish from the menu. It is also possible to set a macro by simply typing /fish into an empty macro slot.
Unlike other crafts, fishing requires a certain degree of interaction in order to achieve results. Wait a few seconds for a bite. When a bite comes, the fish's stamina bar will appear in the target window. The rod will pull to the left and the right. If the camera is facing the back of the player character, move the directional buttons in the opposite direction the rod is pulling to lower the fish's stamina (its HP bar), stop pressing anything when the fish's stamina hits zero, and press enter to reel it in. If the player continues to press a directional key after the fish's stamina hits zero (the stamina bar will go dark), there is a chance that it could regain a sliver of health and break the line upon attempting to reel it in.
Fishing puts a strain on the player character, which is commonly known as "fishing fatigue". It does not affect any other aspect of the character other than fishing performance. Fatigue resets itself back to normal when the day changes, at Japanese midnight (real time). Different catches carry different amounts of fatigue along with them (small fish usually carry minimal fatigue). As fatigue rises, bite rates may drop and it can become more difficult to catch certain fish, as fish stamina bars will not decrease as quickly. When fatigue reaches its maximum (after successfully reeling in around 200 fish and/or items), the player will no longer get any bites, effectively limiting the total amount of fishing one can do every day.