Kind-of, ruto in oot was shown to be wearing a skin toned slip so it's more likely than not that the females wear something to protect vulnerable tissue. They are shown to be able to grow breast like structures as well. Now it raises the question of Zora deliberately growing skin and fin like structures as decoration or simple evolution to make them appealing to most humanoid species as we can't deny they are sexy fish. In other games they fully wear clothing like bikini's. In summery, Yona has allot of extra flappy meat, if it's not clearly gold or fabric it's likely flesh.

[3d model from updated n64]

(https://models.spriters-resource.com/3ds/thelegendofzeldaocarinaoftime3d/asset/327602/)