Really enjoyed the fire eel, you should try to change her substrate to a thinner sand so she can bury herself and try to put some driftwood so it has a more natural look to it.
I switched from some thick gravel to this black sand that I have currently but I feel the white beach sand would be perfect for her. I can probably move one of my driftwood pieces from my 125gal to that 40gal. Thanks for the comments