This mystery can be found in the southwest of Glowecestrescire, just west of Glowecestre, AC Valhalla.
Where to Find Small Bullhead Fish
To complete this mystery, you’ll need to find 10 small Bullhead fish. These can be found in most rivers throughout the game world, including the Afon River just south of the altar, but you’ll find good concentrations of them in the Nene River, which runs just south of your settlement at Ravensthorpe. You can capture them with your fishing line, or shoot them with your bow. You’ll find that you’ll fish out plenty of other fish species while you’re fishing for bullhead, but if you keep at it, you’ll eventually get the 10 required. One of the most effective methods is taking a small rowing boat and shooting fish around you as you row, while using Odin’s Sight to highlight them in the water.
Once you have all 10 small Bullhead, return to the altar and make the offering to complete the mystery.