The Picts were a group of people who inhabited Scotland before the arrival of the Scots from Ireland. Their exact origins remain a mystery. They left few written records, but some striking symbol stones, including the stone in the manse garden at Glamis, Angus, which dates from the 7th century or perhaps later.
The manse stone shown below is renowned for its accurate depiction of an Atlantic salmon, incised between a viper (above) and mirror (below). The illustration is believed to be heraldic. Its accuracy suggests that the image of the fish was produced by drawing an iron spike around a fish in situ and with the principal fins teased out by hand.
For further information, see Shelton, R.G.J. 1993. Fish imagery in art: the Pictish standing stone at Glamis. Environmental Biology of Fishes, 37, 160.