Muhammad and Sanam Hussain made the discovery as Sanam was cooking a curry yesterday at their home in Alum Rock, Birmingham.
Sanam, who is seven months pregnant, said the sight of the creature had made her feel ill.
"It was disgusting. I am in shock. I am so worried about my baby because I am pregnant, she said.
"I talked to my midwife about it and she said if I feel ill, I should contact the hospital," the BBC quoted her as saying.
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"My wife was making lunch for me and our 15-month-old son," he said.
"When she opened the can, she saw something and screamed at me to come through. I saw it was a dead baby lizard.
"We are worried about food poisoning. The can was part of a pack of 12. We had already eaten seven of them. Now my wife is off her food. I think we have been put off tinned tomatoes for life," he said.
Muhammad said he had bought the cans at Masala Bazaar, an Asian supermarket in Birmingham which is owned by Euro Foods.
Euro Foods said it had contacted its Italian supplier to find out how the lizard got into the tin.
"This is a major concern. We are in touch with the family and are going to collect the offending can and have it analysed to see at what stage of the process the lizard got introduced," the company said.
"Once we have investigated, we will put in controls to stop this happening again," it said.