The Elverwatcher is based on a digital scanning camera and computer vision. The small eels passing through the camera are recorded and our custom designed software is used to analyse the images and count the individuals. The software shows a graphical representation of the position and quantity elvers passing through the counter across the scanning area. An even spread of fish across the scanning area will give maximum capacity and accuracy.

The Elverwatcher can count juvenile eels from 0.1 g and it can show the real time camera image of the scanning area to view how the small eels

pass through the counter and identify any obstructions or objects that might remain in the camera´s field of view. The outer diameter of the flange is 330x140 mm and the inner diameter is 226x100mm.

See layout drawings


Elverwatcher Software


The main screen


migrade chart

Migrade Chart

Presents migration distribution of the counted fish.





View recorded images.





Used to check if the camera is correctly positioned and the amplification of the light is correct.





Shows the position of the fish in the counting unit.



Counter calibration

The Calibration function calculates a new position automatically. Press “Calibration” button on main screen with no water running through the counter.

It is also important that the lamp has been on for five minutes or more and the mirror and camera window are clean. Wait until counting message appears on bottom left of screen. It is good practice to re check the “Visibility” graph. If the edges of the scanning area are still not acceptable then it may need to be done manually.