I don't think it's an Anguilla, it has no pectoral fins. I purchased 3 eel less than a month ago that were labeled as a Marbled Anguilla(spelled horribly wrong on the tank). But I'm pretty sure what I bought was a Marbled Swamp Eel, Synbranchus marmoratus.
Although now that I look at more pictures, I might have received two of the three different species of Synbranchus.
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252005000300001
Yours might be Synbranchus lampreia, but I don't see any photos online that show the stripe down the back like yours.
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