a lot of different fish can go in there, they dont seem aggressive except slightly when its feeding time. they seem to get euphoric from the smell of food. some people will say not to put them in with aggressive triggers ( clown, queen, undulated ) because the trigger might find the eel to be a "chew toy", but the more passive ones are fine.
snowflakes eat almost anything, imo. silversides, krill, squid, clam, etc. variety is good, too, so feed all kinds of stuff.
did the tank cycle with the eel in it? they are rather hardy and often will survive tank crashes or infestations with bacteria, ich, etc. i love my eel, im rambling on now, sorry bout that. good luck!