Hanoi (dpa) — Fireworks, family dinners and cash-stuffed red envelopes – Lunar New Year traditions vary widely across Asia, but none are quite like Vietnam’s ritual of releasing carp into lakes and rivers.

On Friday, March 2, people across Vietnam will release living fish into nearby waters – and also cook up a feast of chicken, spring rolls and other dishes – in a day of traditions held before the Tet holiday begins.

The fish are released to pay respect to the so-called “Kitchen Gods”. According to Vietnamese mythology, these three goods ride a carp to heaven every year to report to the Jade Emperor on the activities of every family.

To appease the carp-riding gods, families come together on the eve of Tet in belief that their luck for the next year depends on it.

While releasing carp into a lake in Hanoi, 32-year-old Duong Huyen told dpa: “I believe the Kitchen Gods will ride these fish and fly into heaven to report to the Jade Emperor about what our families have achieved over the past year.”

The tradition has, however, also developed into an environmental issue in recent years, and environmentally conscious Vietnamese have campaigned to stop people from polluting rivers with plastic bags while releasing fish.

“Many people release fish into the Red River from Hanoi’s Long Bien Bridge,” Pham Thu Hang, 42, told dpa. “But they also throw in the plastic bags containing the fish, and end up polluting the river with rubbish.”

The spike in fish population in certain waters when a large groups of people simultaneously release living carp has also brought unwanted consequences.

“All families want to release golden carp into clean lakes or rivers,” she says. “However, in many places, families release them into the same lake and overpopulate the lake, and many fish die a few days later.”