A Brazilian family is in a critical condition after eating one of the world's deadliest fish for dinner.

The Souza family cooked and served up the puffer fish, which a friend had caught during a day's fishing.

However, they were all unaware that the fish contains a toxin 1200 times more lethal than cyanide, a drop of which can kill within 24 hours.

The 11 members of the family became violently ill just seconds after they took their first bite of the meal.

Everyone in the family, including four children under the age of six, started to vomit and lost the feeling in their faces, legs, and arms and then became totally paralysed.

Christiane Souza, whose husband Jose Augusto ate the fish, said she invited the whole family to what she thought was going to be a delicious fish feast.

"The fish looked so tasty so we invited the whole family. We fried it and everyone tucked in," she told Brazil's RJ TV.

"They were all saying how delicious it was. I didn't eat it because I was waiting until everyone had tried it.

"My husband was the first to say he couldn't feel his tongue, then his face, and then his arms. Then his legs went dead and he couldn't stand up anymore. It was terrifying."

Grandmother Maria Do Carmo didn't eat the fish either, and said her grandson, daughter and son-in-law were all fighting for their lives.

"We're praying for a miracle," she said.

Puffer fish is considered a delicacy in Japan, but chefs have to undergo two years of training before they are permitted to cook the fish to customers.

There is no known cure for the poison, which paralyses and suffocates the victims while they are still awake, The Metro reports.

News break - October 27