The Fish Stone is an Old Red Sandstone monolith set upon the pasture terrace of the Usk, 4.5m high by 0.9m by 0.45m, carved to resemble a fish standing on its tail. It was very likely erected in the Early Bronze Age as a ceremonial monument, but may have been re-used as a medieval boundary marker. It is set within and possibly associated with: Penmyarth Park (NPRN 86096).

Edited from Briggs, C.S., 1997, An Inventory of the Ancient Monuments in Brecknock (Brycheiniog), Part i, RCAHMW, p174-5, SS29.
T. Driver, 26 July 2007