Health authorities are warning people to think twice before buying fresh whitebait online.
Auction website TradeMe announced it would allow people to sell the fish, this week.
Whitebait was one of the few types of seafood that any person can legally sell.
But Canterbury medical officer of health Dr Alistair Humphrey said with all the food poisoning he sees, he certainly would not be buying whitebait online.
"How could you ever know what the source of the whitebait was.
"We all like whitebait that's come from a nice, clean river and there are some rivers which are clean, but there are some rivers that whitebait where can be fished from that are absolutely filthy and you would not know online where that stuff has come from.''
TradeMe said it would consider stopping members listing whitebait if there was concern about food safety, and the Government said it could issue fines and prosecute if people got sick.