eel? FW? Then it would just be a FISH then with a cool name like "fire eel" etc to help sell it better. True eels gotta be in salt water even snowflakes...they start out in FW/brackish water to start out with when young then as maturity kicks in they go to saltwater......kinda like the people who mistake green spotted puffers as "freshwater" fish. Start GSP's that are 1-2 inch FW....3-4 inches brackish water.... 5-6 inches salt water.
that would be a boring pond, make sure to get some mates. I own a few SW eel's and they like to hide most of the time....in a pond, I dont think you would even ever see them unless you planned on scuba diving.
a large electric eel would be cool again not a true eel but really are you buying it beacuse it has eel in the name?
they dont move around too much
plus if you dont put alot of decoration in the pond you could see it better.