Muyu [Chin.: mùyú 木魚 | Jpn.: Mokugyo] - Literally "wooden fish". An elaborately carved wooden drum struck with a padded wooden stick during Buddhist chanting services. Fish, since they never sleep, symbolize the alertness and watchfulness needed to attain Buddhahood.

This “Wooden fish” is a percussion instrument used by monks and laity in the Mahayana Buddhist tradition [Chin.: Dàshèng Fójiào 大生佛角 | Sansk.: Mahāyāna]. It is often used during rituals usually involving the recitation of sutras [Chin.: Fójīng 佛经 | Sanskr.: सूत्र sūtra] or other Buddhist texts. The wooden fish is mainly used by Buddhist disciples in China, Japan, Korea, and other countries where the practice of Mahayana, such as the ceremonious reciting of sutras, is prevalent.

In most Chan Buddhist traditions [Chin.: chánnà ??], the wooden fish serves to keep the rhythm during sutra chanting. In Pure Land Buddhism [Chin.: Jìngtǔ fójiào 净土佛教], it is used when chanting the name of Amitabha.

The Muyu along with a large temple bell and drum, It is found suspended in front of Buddhist monasteries. When proceeding with various duties (such as eating, lectures, or chores), a monk and a supervisor utilize the instrument to call all monastics to go to their tasks.

These are two kinds of wooden fish: One is round in shape with scales carved on it. It is said that fishes don’t close their eyes when sleeping to remind the chanting monks to be concentrated. The other is rectangle in shape, suspending in front of the dinning hall of a Buddhist temple. When having breakfast and lunch, the monks beat it to produce rhythm.

As for the origin of the wooden fish, there is an interesting legend:

Many years ago, a Chinese Buddhist went to India to acquire scriptures. One day, on his way to India, he found himself blocked by a flooding wide river. Neither a bridge nor boat, could be found near. That moment, a big fish swam up, and assisted to help him cross the river. In the middle of the river, the fish said to the Buddhist, “Because I have committed a crime, I have been sentenced to live in this river for many years. Now I am told that you are going to India for scriptures, so I come here to help you, just to atone for my crime. A good deed I do! If you meet Sakyamuni, please ask Him when I can become Bodhisattva”.

Being anxious to cross the river, the Buddhist accepted the fish’s demand without hesitation. After having spent 17 years in India, the Buddhist went back to China, taking the scriptures along with him. On the way back to China, he came near the former river, which was flooding furiously again. While he was worrying, the big fish appeared and gave him a hand again. In the middle of the water, it asked the Buddhist, “You have been in India for many years. Did you ask Sakyamuni when I can become Bodhisattva?” The Buddhist replied, “Ah, Sorry! I forgot”. On hearing this, the fish got angry. It vibrated itself only to get the Buddhist and his scriptures slided into water. A fisherman who happened to pass nearly helped him out of water, unfortunately, the scriptures were scattered by the flood.

The Buddhist came home, full of anger. He said to himself. “It is the fish who made my 17 years of efforts wasted”. Then he carved a fish head with wood, that is, the wooden fish. When he recalled his adversity, he beat the wooden fish with a wooden hammer. To his surprise, each time he beat the wooden fish, the fish opened its mouth and vomited a character. He became so happy that whenever he had time, he always beated the wooden fish. As the years passed by, he got back all that he had lost in water from the wooden fish’s mouth.