Pool filter sand or EcoComplete are going to be your best bets, since the fire eels like to bury themselves. Don't get the Tahitian Moon sand, as that has sharp edges that can hurt the fish while it's burrowing.
They can uproot plants and move
driftwood around, so don't count on rooted plants, and don't stack anything that can fall on them while they're shifting around.
Any filter (I presume that's what you mean by pump) should work fine.
"Fire eels will take a wide variety of food including tubifex, fish,
brine shrimp, mosquito larvae, bloodworms, mussels etc." (Wikipedia)
They also need a tight-fitting lid, as they are escape artists.