Between 1 and 4 seen throughout the day moving stones to make nest areas.
No interactions present.
Don't know enough about fish to click on 'I agree', but I like the photo!
Entomologist and biological recorder
Glad you like the photo - and a rare sight; only the second nest-building I've witnessed. Also, a free lamprey identification guide is available at:
Lat/Lng: 51.0, -1.2
OS grid ref: SU5631