Murdoch Fonda Munro had nine dozen shucked Pacific oysters stacked in his fridge.
He wanted to sell them and posted on a Facebook page advertising the tasty sought-after morsels as "picked, shelled and cleaned today".
At $20 a container it was a bargain - but totally illegal.
For the 47-year-old Whangarei scaffolder it wasn't cash he made from using social media but a court date when officers from the Ministry of Primary Industries were alerted to the post.
Munro was fined $1000 and ordered to pay costs after he was found guilty of possessing rock oysters for sale without a licence, after advertising them for sale on a closed Facebook group in October 2017.
The Whangarei District Court heard Munro posted multiple images showing shucked oysters in takeaway containers onto the closed Facebook group, "Buy Sell Swaps Whangarei", asking for $20 a punnet.
It was not clear whether he made any sales but, when Munro was interviewed by officials, he explained he knew he was not able to sell recreationally sourced seafood, but he was not thinking straight at the time.
Munro was not a commercial fisher, licensed fish receiver or a marine farmer who were, with the correct paperwork, permitted to sell seafood.
The maximum fine for the charge was $250,000 and/or judges can order a community-based sentence.
The sale of recreationally caught fish in New Zealand was illegal. Only fish legally caught by commercial fishers may be sold.
MPI said New Zealand had a serious problem with the unlawful sale of oysters to service a large blackmarket trade to domestic customers, local restaurants and takeaway bars.
There were many rules for what people, groups and businesses can and cannot sell on Facebook. For more details go to www.facebook.com/business/help/community.