Conger Eel
Anago
noun
A hole child isn't some kind of creepy hole child (not sure how else to describe it). It's a conger eel, a type of tasty eel eaten in Japan. It might be easier to learn the reading first, though, and use that, because the second meaning option is anago, the Japanese word for it (also used in English).
The reading is the two kun'yomi vocab readings combined. So, 穴 and 子 to combine make あなご. Just watch out for rendaku, which changes the reading of 子 from こ to ご.
今日はお昼に穴子の天ぷらを食べました。
Today I had conger eel tempura for lunch.
穴子の身はやわらかくて、食べやすいです。
The flesh of anago is soft and easy to eat.
アメリカでは穴子は手に入りにくいので、代わりにウナギが使われています。
Since it is difficult to get conger eel in America, freshwater eel is used instead.