Sorry to hear about your experience with the eel Deb ... the biggest fish I lost was a saddleback clown ( just big enough to be swallowed apparently
)
He lived quite happily with a large atlantic tang, naso tang, sohal tang, 2 yellow tangs & a foxface for the past few years ( sohal being the newest addition just before tearing that tank down )
I never fed him silversides though ... only tiger prawns every other day and he never bothered the large fish ... they actually chased him away as I would put 2 shrimp on the pvc tube and the tangs would try to eat both but most of the time he would snag one of the shrimp
Maybe changing tanks changed his personality somewhat and he felt threatened by the fish in your tank somehow ... too bad as he was one of my favourites and I would buy him back if I had somewhere to put him ( have to finish developing my basement first and build a new tank/tankroom )
whoever gets him will have a awesome eel