Why a Fish Pouch Could Become Money
When federal prisons restricted smoking in 2004, cigarettes lost much of their usefulness as a dependable trading item. In their place, pouches of mackerel fillets—often called “macks”—could fill a practical role: they were recognizable, portable goods that prisoners could trade even if they did not want to eat them.
That is the basic logic of commodity money: an ordinary item serves as a means of payment because people expect others to accept it. A pouch could be exchanged for another commissary item, a service, or contraband. Its usefulness as food gave it some underlying value, while its packaged form made one unit easy to identify and pass along.
Scarcity Made Each Pouch More Useful
Commissary limits mattered. If a person could buy only a limited number of pouches, the supply available for trading was constrained. That helped make a pouch more than just a convenient snack: other prisoners had reason to believe it would remain difficult to obtain and therefore worth accepting.
The system did not need an official exchange rate or a central authority. People could agree on what a service or item was worth in pouches, then adjust those informal prices as supply and demand changed. A currency works only when others trust they can spend it later; repeated trades help sustain that trust.
A Currency Built on Everyday Constraints
The mackerel pouch’s role grew from the conditions of prison life, not from a formal decision to create money. Once cigarettes were less available as a trading medium, a limited-quantity commissary item could take their place. The striking detail is that a sealed packet of fish could circulate as payment precisely because it was both ordinary enough to obtain and scarce enough to matter.
