Blockchain. It's the buzzword in startups. The digital transaction technology backs cryptocurrencies, like bitcoin, that we hear so much about. But business plans abound to give every industry a blockchain makeover, from real estate to drug prescriptions. And companies focused on sustainability see a particular opportunity to verify every step a product takes on the blockchain. Jayson Berryhill is doing that for seafood. Marketplace’s Jed Kim sat down to talk with him about a new project called Fishcoin. (10/18/18)