The fish do­or­bell

The Fish Doorbell is currently offline and will return on March 2, 2026, for a new season.

Each spring, fish swim from the River Vecht, through the Oudegracht and the city’s canals, toward the Kromme Rijn. They pass straight through the heart of Utrecht, searching for a place to spawn and reproduce. Sometimes, they have to wait a long time at the Weerdsluis (Weerd Lock), because in early spring, the lock gates don’t open very often. That’s why there’s an underwater camera installed at the lock.

Spot a fish on the livestream? Ring the online Fish Doorbell! The lock keeper will get a notification and, if many fish are present, open the lock to let them through. This way, you’re directly helping fish continue their migration route. The Fish Doorbell will be live again on March 2, 2026.

The lock itself is a sight to behold — a 200-year-old monument. Each time it opens, around 1.5 million litres of water flow through. The difference in water level is nearly a metre. The lock allows the water levels in Utrecht to be controlled with centimetre precision.