Urokuzu

…The word sakana has been used since the Middle Ages to refer to fish, but it was originally called uo or io, and was also called irokuzu or urokuzu because of their scales. It is said that fish came to be called sakana, meaning "sake vegetables," because they were often served at drinking parties, and became the representative side dish for drinking. …

*Some of the terminology explanations that mention "Urokuzu" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…〈さかな〉は中世以来の魚類を総称する語であるが，もとは〈うお〉もしくは〈いお〉と呼び，また，うろこのある点から〈いろくず〉〈うろくず〉とも総称した。魚類が酒席に添えられることが多いために，酒のな(菜)の意で〈さかな〉と称せられ，飲酒の副食物の代表となったと説明されている。…

※「うろくず」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報