from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A small Japanese fish (Oryzias latipes) commonly found in rice fields and often used in biological research or in stocking aquariums.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A small Japanese ricefish, popular for use in aquariums.
Japanese, killifish : me, eye + daka, high.(American Heritage® Dictionary of the English Language, Fourth Edition)
Japanese メダカ. (Wiktionary)