The good news is that it's not uncomon for eels to fast for periosds of time. A month is not too long and the eel will be fine not having eaten for a few weeks. It may have been the stress of the move which triggered the hunger strike. If the eel is otherwise healthy, it should resume eating on it's own. Shrimp is okay, but like any marine organism, having a varied diet is best. Try some small scallops, pieces of squid or octo. Even some pieces of clam might work.
You could also try some live foods; ghost shrimp sometimes entice predators. If you want to really simulate it's natural diet, and have a few bucks to spend, toss in a couple of small sally lightfoot crabs or mithrax crabs. Overall, I wouldn't worry too much. Watch for listlessness, weight loss, or other symptoms.
Post your water parameters (real numbers). As tough as eels are, they can also react to deteriorating water. What size tank is he in and is there enough rock for him to totally conceal itself? Other tankmates?
