My advice and experience with Elephantnose would be to put him in a quiet tank with a few gentle fish that won't either interfere with them or even think about bullying them off of food. (quiet tetra) Offer live/frozen brine, bloodworms and put them right in front of your guy with a syringe. Like Dragon eels they are fine usually once they are eating but if it takes too long to start them or they don't get mothered they wither away and die.
Also they don't do well with Knife fish or dolphin whales or baby whales other elephantnose or other fish that emit electrical discharges to locate. They want cover....either natural plants or tubes to feel secure.