Central Aquarium have some Eels similar to that back on black Friday, saw a few still there a couple of week, but didn't see any today.
What you can do is get a container with a lid, put some holes in it, and put in some pieces of rock or PVC, and then place the Eel in it and then into your sump. That will let you keep it in the sump and you can fed it in the container, which will make it easier for the Eel to find the food, also you wouldn't have to worry that it will climb out or get sucked up into a pump.
They had a number of different ones, which includes some of the more common green or brown Eels. One that they I was able to Id was the Brazilian Dragon Eel, you could even see the small horns on the head.
It's extremely hard to tell from the picture what type of Eel it is, it just moves too fast and you can't see it clearly enough. It's definitly a type of Moray though.