Fish = 鱼 [yú]
Someone has a paper fish stuck to the back of his shirt: the French April Fools’ prank, the “April fish.” That fish is a 鱼.
鱼 (yú) means “fish,” both the animal and the food. Count fish with 条 (tiáo), the measure word for long, thin things: 一条鱼 (yì tiáo yú).
鱼 sounds the same as 余 (yú), “surplus.” That is why fish is served at Chinese New Year, with the wish 年年有余 (nián nián yǒu yú), “may every year have plenty.”
我不吃鱼。 — Wǒ bù chī yú. — I don’t eat fish.
河里有很多鱼。 — Hé lǐ yǒu hěn duō yú. — There are lots of fish in the river.