noun
water flea; Daphnia
Small freshwater crustacean of the genus Daphnia, often used as fish food or observed under a microscope. The word is usually written in katakana.
池の水を顕微鏡で見ると、ミジンコがたくさん泳いでいた。
When I looked at the pond water under a microscope, many water fleas were swimming around.
金魚の餌に乾燥ミジンコを与
I feed dried water fleas to my goldfish.
The word is a compound of 微塵 (mijin, 'tiny particle') and 子 (ko, 'child'), referring to the creature's minute size. The katakana spelling is standard.