Why Prisoners Pay Each Other In Fish

Delicious canned mackerel is being used as currency in America's prison system.

Canned mackerel is one of my favorite varieties of tinned fish, and it's a valuable addition to any meal—but some people place a much different value on it than I do. The Wall Street Journal reports that Sam Bankman-Fried, convicted of fraud in the collapse of cryptocurrency exchange FTX, has ditched his Silicon Valley currency of choice and is spending with a different type of coin: packaged mackerel. It turns out that in the U.S. prison system, mackerel is a common stand-in for cash.

Why mackerel is valuable in prison

Picture two people bartering in prison and your mental image of the exchange probably involves a sneaky handover of cigarettes. But it's 2023, and cigarettes have long been banned in United States prisons (since 2006, when they were removed from commissary shelves). Still, inmates need something to trade for goods and services within the prison system, and that's where mackerel comes in.


WSJ explains that mackerel has become the favored currency since the cigarette ban. Pouches of the fish, available for purchase at the prison commissary, are often as good as cash. They're referred to as "macks," and Bankman-Fried was reported to have traded a few packages to an inmate in exchange for a haircut ahead of his sentencing trial.

Bankman-Fried is currently being housed in Brooklyn's Metropolitan Detention Center, whose commissary inventory (as of 2020, at least) includes various food items such as summer sausages, blocks of Velveeta, candy, packaged meals, and pouches of fish, not only mackerel but also tuna in two varieties (plain white and Thai chili sauce).

The Foundation for Economic Education (FEE) explains that since mackerels have long been worth roughly $1 at the commissary and are generally unpopular as food, they make for a good substitute for cigarettes as currency.


The FEE cites a video by podcast Wall & Broadcast in which inmates explain just how the mackerels function as currency. One inmate put it this way:

Mackerel had utility because it was inherently inflationary. A certain amount of macks came into circulation every day. Every inmate can only buy 14 mackerels per week. 14 times 500 inmates times 52 weeks is the amount of mackerels that are coming into circulation every year, and that's why it was a pretty good stable value of currency.

And because the mackerel isn't being eaten, it doesn't exit the internal prison economy, instead continuing to circulate like money.

I usually keep a few cans of mackerel at home in my pantry for when I'm hungry and don't want to bother heating anything up. But I never knew that this rich, oil-packed fish carried an underlying value for so many people. It makes me appreciate my delicious yet simple lunch that much more.