
In the central Dutch city of Utrecht, a unique initiative called the “fish doorbell” has captured the attention of millions worldwide.
An underwater camera at the Weerdsluis river lock streams live footage to a website, allowing viewers to spot fish waiting to pass through during their spring migration to shallow spawning grounds. When someone sees a fish, they can press a virtual button (nicknamed the “fish doorbell”) sending a screenshot to organizers. Once enough fish are spotted, a water worker is alerted to open the lock, helping species like bream, pike and bass continue their journey.
Now in its fifth year as of March 2025, this quirky blend of slow TV and ecological activism has become a global hit. The stream often shows just murky green water with occasional bubbles, but as spring progresses and waters warm, more fish appear, delighting viewers.
Beyond entertainment, it’s a lifeline for these native freshwater fish which can get stuck behind the lock and become easy prey for predators when boat traffic is low. The project, dreamed up by ecologist Mark van Heukelum, has turned into an unexpected sensation, proving that a simple, feel-good idea can hook millions!