I've got a 16 inch SAL and a trio of Yo-yo loaches (Botia almorhae). The lungfish has never bothered the loaches, but they sure bother the hell out of him. Mostly they just swim around his head or tail during the early evening hours, until the lights go out. Sometimes I think they must think of him as a Really Big Loach, since they were there before he was, and have been around him since he was just a baby. I recently got him a piece of PVC tube to hide in, and since then the SAL seems more relaxed and the loaches aren't dumb enough to go into the tube with him.
Wouldn't say I recommend pairing loaches with lungfishes, but nobody's gone missing yet.