SBF, the former CEO of the collapsed cryptocurrency exchange FTX, is now in prison using mackerel as currency to pay for services such as haircuts, according to the Wall Street Journal. Since the cigarette ban in 2004, mackerel, popularly known as "macks" in federal prisons, has become the currency of choice. Mackerel is not immune to inflationary pressures from the outside world, as well as prison demand, with a reported cost of $1.30 to buy a pack of mackerel fillets through the commissary at the Brooklyn Jail, up 30% from $1 in 2020. （The Block）