hmmm, how large is the eel?
What are you feeding it? Live shrimp? Krill? Silversides?
Did you see it eat at the LFS?
My snowflake went for several weeks without eating when he was first brought into the LFS, we finally got it to eat crawfish, now he eats live SW shrimp. I just dump in 50 and when there gone, I get some more, takes him a week or two to eat all of them. If the eel is large...it may be a very serious problem, large adult fish have a tendency of starving themselves. If you know he was eating at the LFS, he will probably eat for you, it may just take more time. If all else fails, get it a small octopus, they are irresistible to eels.