Fire eel help

[Tuckerp]

I've had a fire eel (about 6" long) for almost a month now. The tank it was in at the lfs was bare with a thick bed of course gravel and all the eels had buried themselves.

My tank has sand substrate with lots of rocks, driftwood and general cover for the eel. Could this be why it won't bury itself? I thought that the sand would be a bonus for the eel and encourage the digging behavior. Is it just a defense mechanism? Only burying themselves when threatened?

 

[Eel lover50]

I'm really new to this site/app and to aquariums to begin with. I have had a fire eel for about a month also and I have yet to see him burrow. I have coarse gravel in my tank. II don't know why this is but thought having a similar occurrence might help.