that doesnt sound quite right to me IMO. If they had a fire and contaminates got into the water, its possible it had a negative effect on the eel, if thats the case then they shouldnt have shipped it. I've seen such things happen before and the warehouses do not ship anything until everything is cleaned up and made sure the livestock isnt in any type of danger.
How was your eel acting when you got him? and how was it acting at the LFS? Depending on its behavior, that may be a good indication of the real COD.