The scales of a fish, reptile, etc. in Hebrew are called קשקש or collectively קשקשת . Since they’re a flaky substance that sheds, Modern Hebrew called dandruff קשקשת as well, or in colloquial Hebrew, קשקשים .
יש לך שמפו נגד קשקשים?
Do you (a male) have anti-dandruff shampoo?