Artwork of Amaterasu fishing
North Ryoshima Coast
Fishing is an activity only found in Okami. Amaterasu has several chances to catch fish during the game. Some Fish are needed to advance in the plot but most of the time Amaterasu can just fish to earn Yen or for fun. Amaterasu cannot eat the fish she has caught to refill her Astral Pouch, she also cannot use them in place of Feedbags.
 Fishing Spots
Amaterasu cannot fish on her own, she needs a human to to help her even though they believe that she is helping them. There are three permanent fishing spots dotted around Nippon, each fishing spot has it's own selection of fish native to it however some fishes are found in two places.
You first get to fish in Agata forest after reviving the Guardian Sapling. Kokari will help you fish as he is looking for two different fish. These two fish, The Giant Salmon and the Whopper, are needed to progress in the game. The Giant Salmon holds the key to Tsuta Ruins and after you clear Tsuta Ruins the Whopper is needed to learn the Brush Technique Crescent. All the other fish that can be caught here are found in other fishing spots around Nippon, this is because after the Kamiki Festival Kokari leaves Agata Forest and you cannot fish again till Sei'an City.
You must fish with Benkei on the bridge to Sei'an's Aristocratic Quarter to progress in the game. After flooding the canals with water you must buy the fishing rod Blinding Snow and bring it to Benkei. After he catches the "Living Sword" the bridge will be raised and Benkei will take up a perminent fishing spot near the Mermaid Spring in the Aristocratic Quarter.
 North Ryoshima Coast
There is a fisherman on sitting on a pier on the Southwestern Island. After you bring him the Marlin Rod, catch the Giant Marlin and bring it back to Umi's Restaurant where you can learn a Secret Brush Technique, you can fish with him any time at that pier.
Kokari goes to Kamui when he leaves Agata Forest. After you revive the Guardian Sapling here you can fish with him. His fishing spot is near the Dojo.
After you have accepted to fish you will get a view of the water and the shadows of fish swimming in it. All the fish shapes look the same however some of them are bigger than others giving you an idea of what fish it might be. You can catch the fish by using the Celestial Brush to draw a line from it's shadow to the rod, When the fish gets hooked all the other fish shadows disappear and two meters appear on screen, a fish stress meter and the fisherman's health meter. The fish can be reeled in by pulling in the opposite direction it swims in.
The stress meter shows the strength of pull on the line: blue means it is weak, green means you have a good pull on it and red means you are straining it. The Health meter shows the condition of the Fisherman, it starts out on green but every time the stress meter hits red it will decrease. There is a yellow warning stage the red where the fisherman is nearly exhausted.
When the fish is close to catching an icon will appear on screen. Tap a random button (swing remote upwards on the Wii Version) and the fish will jump out of the water. You must then Power Slash the fish to stun it and consequently pull it out of the water. Big fish will sometimes require two or even three slashes to stun them, regardless of any Power Slash upgrades.
After you catch a fish you have the option of continuing or leaving, the more fish you catch the bigger they become. You can also end the fishing at any time by pressing the menu button. To catch a fish needed to advance in the plot you usually have to catch two smaller fish before it. The fishing session will also automatically end if the health meter runs out or if you have been reeling in the same fish for too long.
 Selling the fish
All Merchants will buy fish from you however some such as the Taka Pass Merchant or the Tool Dealer in Sei'an City will buy certain fish for more than anywhere else. Apart from three fish all the fish caught in Kamui seal for the same price everywhere.