Even after you and Tulin have helped Rito Village with its massive blizzard problem in The Legend of Zelda: Tears of the Kingdom, they are still going to need you to help them with some small tasks here and there. Stick around the village after you have finished the Wind Temple and talk with the locals to see what they need help with.
This is how you will find the quest Fish for Fletching, which has you finding a specific kind of fish for a Rito villager. So if you are looking to figure out how to start this quest, and see it to the end, lucky for you, it's not too difficult to do.
Starting The Quest
You can't start the quest until after the Wind Temple has been completed, and the blizzard has been taken care of. Once you have done this, you can find a villager, Bedoli, near the top of the village. They are standing out on an outcropping that has a balloon on it, and a bunch of boxes that Bedoli is overseeing.
If you speak with her, she will say she is needing three Glowing Cave Fish, and if you are able to get them for her, she will give you 10 arrows in exchange. It sounds simple enough, but the issue is that she doesn't tell you anything about where you can actually find these fish. Fortunately, they are pretty common and can be found in all kinds of places, if you know where to look.
Completing The Quest
In order to complete this quest and find the Glowing Cave Fish, you are going to have to find an underground cave or a well. These are littered all around the map, and you can go into just about any of them and the odds of finding the fish you need are pretty good.
However, if you want a place that will guarantee it, you can go to the Mabe Village Ruins, which you can find to the southeast of Lookout Landing. When you arrive at the ruins, you will find a well in the middle of town, and you can jump down to find a small pond with plenty of Glowing Cave Fish to choose from.
Hop in the water and take three, or all of them. Once they're in your possession, you can warp back to Rito Village and bring the fish back to Bedoli at the top. When you hand her the fish, she will give you the arrows and thank you. They are just normal arrows, as well, so don't expect anything too fancy.
In addition to this, she will also tell you about the children of the village's favorite kinds of food, and that if you ever bring her Brightcaps or Chillfin Trout, she will give you more arrows. This is a deal that is infinite; you can bring her either item over and over again to get more arrows. It's a great deal to take advantage of if you are ever short on arrows.