My mistake.

I just looked back in your thread and saw the eel was 19 inches already. If he is not already full grown, he is very close to it. At some point when the water parameters more closely match his natural envirnment, he behavior might also change to which is closer to how eels act in the ocean.

I would still say you should not get smaller fish that could fit in his mouth. They are preditors and would hate to suggest a fish that could become lunch after your family become attache to them