We feed Nigel ( our Tire Track) bloodworms, which are his favourite, daphnia and chopped mussel, prawn and cockle.
Obviously the food needs to be chopped very small, Nigel is only young but he always comes out for bloodworms and can be tamed to eat from you hand given time and patience.
I have known people have trouble getting food to the eels without the others eating it first, this was overcome by putting the food in a jar with a thinnish neck,and placing the jar in the tank. If you put it in the same place every time then it becomes familiar.
That way the eels learn to go in there to eat.
Clare