Task 1: The Scent of Reekfish
A Sketchy Story
Warp to Castle Town and talk to Telma. She tells you to go to Ashei, on the northern mountain. The map in the back room tells her exact location in Zora's Domain. Exit the bar and warp to Zora's Domain, then head toward Ashei. Speak to her (as a human) to hear a story and receive Ashei's Sketch. Show the sketch to the Zoras outside the cave to hear that the fish in the illustration is a reekfish and Prince Ralis knows a few things about catching them.
Bomblings and Earrings
Warp to Kakariko Village and seek out the prince. By speaking to Beth, you'll learn that he is in the graveyard, so venture to the west end of the graveyard and crawl through the hole. Show the prince Ashei's sketch. He'll tell you that the Reekfish is attracted to a specific type of coral, then hand you his coral earring as an example, which just happens to be in the shape of a fishhook. The earring gets attached to your pole automatically.
Before leaving Kakariko Village, head over to Barne's Bombs. If you have an empty bomb bag or feel you don't need some of your bombs, purchase the bomblings. These nifty devices move themselves in a straight line and explode when they come in contact with their target.
Catch the Reekfish
Prince Ralis told you that Reekfish can be found at the basin near the mother-and -child rocks (two formations, one taller than the other, that jut out of the water). Go there and catch a Reekfish, then sniff it in wolf form to learn the Reekfish scent. These fish take a little longer to catch than your average fish, but you'll get one eventually. If you're struggling, try lightly shaking up and down, but not enough to make the fishing rod go up. The scent leads into the Snowpeak Area, so go there.
Warning: Be quick because the reekfish can get back in the water after a few minutes. The reekfish can't last without water so be sure to position the wolf close to the finish to learn the new scent.
Task 2: To the Ruins
The Reekfish Trail
While following the scent trail, make sure that you do not fall into the cold water while jumping on the ice floes. Also, watch out for the white wolfos, as they disappear almost as quickly as they appear. Usually one head-on jump attack defeats them, although it's faster to just avoid them all together. When you get to the short cliff that is topped by a snowbank, dash into it to make the bank fall and allow you to continue onward.
You'll discover a howling stone near the summit. Match its tune to prompt the golden wolf to appear near Kakariko Village. Then, go south from the stone to reach a large digging spot. Dig there to enter a cave, then transform into a human. Avoid the ice at the beginning, then climb a ladder and some ivy. When you get outside, transform back into a wolf and follow the scent to a battle with shadow beings. Defeat them, then head to the yeti.
Turn into human form before talking to the yeti, Yeto. After a discussion about the Mirror Shard, he'll invite you to a Reekfish dinner and slide away on a frozen leaf. Run into the tree nearby to knock another leaf off, then follow him. While riding the leaf, lean forward to gain speed. Press to bend your knees, and release the button to jump. Swing your sword to rid the path of ice blocks and flying enemies. At the bottom, enter the ruins.