Dutch's city Utrecht has created "fish doorbell" on a river lock, which has become quite popular among the locals and on the internet.
The bell lets people watching the online live-stream alert the authorities when they see fish struggling to swim upstream during migration.
As reported by Associated Press, the doorbell mechanism is quite simple. It is an underwater camera that sends live footage of the river to a website.
When somebody watching the site sees a fish, they can click a button that sends a screenshot directly to the organisers.
After enough fish gather at the lock, they open the lock to let fish pass through.
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The fish doorbell started five years ago, and has garnered million of viewers from around the world who tune in to see the slow life of fish in river.
For most of the transmission, the screen remains murky green but once in a while a fish can be seen, as the water warms up, more fish start to show up.
Without the audience help, native freshwater fish such as bass, pike and bream can become an easy prey for predators.
Mark van Heukelum, who is an ecologist and the developer for the bell, shared, "I guess the combination of a good cause, a beautiful story and just simple idea generates all this attention."
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Notably, a lot of viewers treat the live footage as a slow television and find it relaxing, while others feel happy to directly help the journeys of fish.
