Blue lingcod: Though usually white-hued like halibut or cod, lingcod, a West Coast bottom-dwelling species, occasionally looks as though it's been marinated overnight in a tray of Blue No. 2 food dye.

Part of the fun of collecting is learning something extra about the history of the piece. This fish-shaped vase was sold at a Cowan auction in December 2015. It was described as “a hand-painted ...