I love peacock eels and have kept a few of them over the years. They are among the less aggressive of their species but are still predators. I was able to keep them with larger tetras just fine. Black skirts and serpae. Also with yellow barbs and sailfin molly. They will eat shrimp, mine ate ghost shrimp, and they will sometimes catch and eat fish if they can get them. Generally those fish that stay near the top of the water column are safe, at least that's how it was for me. The eel really didn't go up there.
So, my experience is, yes, you can keep other fish with them but you need to be selective.