ENDANGERED twait shad have been spotted swimming past the Diglis Fish Pass observation window in a new video.

The video was shared by the Unlocking the Severn Team, who are behind the Diglis Fish Pass.

The twait shad are the reason behind the development of the project.

A spokesperson for Unlocking the Severn said: "The fish are shad. We are seeing lots moving through Diglis Fish Pass now, on their way upstream to find good habitats for spawning.

"Diglis fish pass was complete for the shad to swim through last year, but 2022 is the first year all four fish passes are complete along the Severn, so as you can imagine we’re especially excited to see them making the journey this year."

READ MORE: Moment biggest shoal of fish yet swim by Diglis fish pass

The Diglis Fish Pass contains a room below the River Severn, with a large viewing window where fish can be seen making their way upstream.

Two cameras are stationed in the viewing room, which both monitor every fish which passes through.

The viewing window is illuminated with a backlight so that the cameras can detect fish at all times of the day.

Fish that can be seen at the window include twait shad, dace, lampreys (or vampire fish), pike and even salmon.

The purpose of a fish pass is to allow fish to move past manmade blockages in water. In Diglis, the weir means that many fish looking to travel upstream struggle due to the two-metre separation.

The pass consists of 11 small pools, each just 20 cm higher than the last, making it more manageable for the fish to swim through.

READ MORE: Take a look inside the Diglis Fish Pass

The Diglis Fish Pass is hosting a drop-in session on Saturday from 10am to 12pm.

There will be another special open day event on Saturday, May 21 to celebrate World Fish Migration Day.