tje janitor fish will eat the gold fish
so i recommend to never ever put a janitor fish inside a tank when there are goldfish or any other fish inside it
EXPLANATION: It is advised that we cannot combine a janitor fish and goldfish in a same aquarium. This is because, Janitor fishes are usually a tropical type. And one should not mix cold water fish like Goldfish with tropical water fish (Janitor).
They might both die but they won't kill each other.
They will fight