Where does “魚類” come from?

魚類 (Japanese) comes from Japanese 魚, from Middle Chinese 魚 — fish.

魚類 (Japanese): fishes

Definitions

Step	Language	Word	Meaning
1	Japanese	魚	a fish; a fish, "especially" when used as food; a...
2	Middle Chinese	魚	fish

魚類 — Etymology, Origin & Word History | Etymology Explorer