Under normal circumstances, scavenger fish will not eat small fish. Especially healthy small fish, scavenger fish will not eat them. However, scavenger fish will eat dead small fish, or if the small fish is dying and is terminally ill and waiting to die, then scavenger fish may eat it.

Extended information:

Notes on scavengers:

In fact, this kind of fish is suitable as a scavenger because their habit is to suck algae and benthic animals. But avoid mixing it with gentle or small fish. If they reproduce in large numbers, they will eat other fish eggs and lead to the extinction of other fish. There are no natural enemies in China yet, so treat with caution. It cannot be released. This fish has overrun in some places in the south, causing the native fish in the entire river to become extinct

Reference: Baidu Encyclopedia Scavenger