Aarau marks 500 years of its illuminated Bachfischet tradition

Aarau is celebrating the 500th anniversary of the Bachfischet, a city festival rooted in the annual cleaning of its artificial Stadtbach watercourse, SRF reports. Schoolchildren marched through the darkened old town with handmade lanterns while drummers announced the night procession.

The lanterns lit up the faces and façades as the children sang, “De Bach isch do, de Bach isch do” in the local dialect. Fish are a popular lantern motif, and some of the lanterns are burned at the end of the procession.

The Bachfischet was first mentioned in an Aarau council record in 1526. The city has no natural river, so the watercourse was artificially created. Historian Stefanie Mahrer said the Stadtbach was the city’s lifeline until the first springs could be tapped.

In the medieval period, the city needed the watercourse for drinking water, firefighting and water power for businesses. Once a year, the town dammed the stream so its bed could be cleaned. The work usually took four days and was carried out as unpaid communal labour.

During those four days, residents had no drinking or firefighting water, so households stored supplies in kettles and tubs. September was considered the ideal month for the work because it fell after the harvest and before the grape harvest, when labourers and containers were available.

The tradition also survived disruptions. In 1784, the cleaning had to be stopped early because of a major fire. The Stadtbach was then refilled ahead of schedule as an emergency measure, according to the Heinerich Wirri guild, which maintains Aarau’s traditions.

Today, the Stadtbach runs underground. Historical footage from 1950 shows the watercourse being dammed and cleaned, with large quantities of waste removed before the sluice was reopened.