Pouches of mackerel fillets became the gold standard of currency in United States federal prisons after smoking bans eliminated cigarettes from the black market in 2004.

A closer look

Pouches of mackerel fillets became the gold standard of currency in United States federal prisons after smoking bans eliminated cigarettes from the black market in 2004. Inmates use these preserved fish to buy haircuts, laundry services, and stolen goods because the pouches possess all the classic traits of sound money: they are durable, portable, standardized, and hold intrinsic value. The commissary strictly limits how many pouches an inmate can buy, inadvertently acting as a central bank controlling the money supply. Wall Street analysts could probably learn a thing or two about stable monetary policy from incarcerated felons trading vacuum-sealed seafood in maximum security cell blocks