I took a friend to a bit of river I occasionally fish, which holds plenty of barbel to a good size. He fished halfway along the backwater stretch, and I dropped in towards the lower end, about two hundred yards away. After not much more than an hour I hooked a good fish and was just wondering how to attract my friends attention when I saw him striding towards me with a bulging net. As he got close he called out that he'd had one. I landed mine, left it in the net to recover whilst I took a quick snap of his, weighed it (8lbs) and returned it in my swim rather than cart it about any more. We noticed it had a distinctive notch in the lower tail lobe. I then fished mine out, weighed it and returned it.
We had no further action until sunset, when I hooked a fish (I was still in the same swim) which put up a fair scrap before conceding defeat. When I parted the mesh to examine it I thought it looked familiar. There in the lower tail lobe was the same notch.
That fish had taken luncheon meat, been hooked, played, landed, carried two hundred yards downstream, weighed and returned, then - after a few hours - taken luncheon meat again, from the same spot where it had been returned earlier.