Wildlife officers described the turtle as the largest they had seen.
Freshwater turtles are one of Queensland's most popular pets, but they are also one of the most surrendered animals as people underestimate the level of care they require.
Manager Southern Wildlife Operations Warren Christensen said the Queensland Parks and Wildlife Service and the RSPCA routinely collected turtles from people who could no longer care for them or did not have a permit to keep them.
"Since 2021, we have had more than 100 turtles surrendered to us by people who didn't have a permit or can no longer look after them," Mr Christensen said.
"Owning a turtle is not just for Christmas. They are a long-term commitment, because freshwater turtles can live around forty to fifty years old.
"When turtles are hatchlings, they are extremely cute, and many people think they can keep them in a fish tank for their life, but turtles don't stay hatchlings forever.
"They require a pond large enough to swim in, plenty of land they can explore for exercise and if they're kept inside, they need a large fish tank and access to ultraviolet light.
"They also need plenty of clean water to prevent infections and other health issues, such as soft shells, cracked shells or peeling shells.
"Many of the turtles that are surrendered to us haven't been looked after properly, are in very poor health.
"Unfortunately, turtles are one of the most difficult animals to rehome, and we can't find new homes for many of the healthy turtles we receive from the public."
Mr Christensen said a 20-year-old turtle was recently surrendered to wildlife officers by a person who could no longer care for it.
"When wildlife officers collected the turtle, they were stunned because it was one of the biggest freshwater turtles they had ever seen.
"The turtle was kept inside as though it was a dog or cat, free to roam around the home and had regular access to food that turtles wouldn't normally eat.
"Luckily it was rehomed at the Walkabout Creek Discovery Centre at The Gap in Brisbane, and it was immediately placed on a diet.
"Unfortunately, many people who surrender turtles to us don't have the necessary permits, and don't always provide information as to where they bought it.
"Any native animal sold without permits is part of the illegal trade of native wildlife, which is a serious problem in Queensland and Australia.
'Native animals being sold without permits may have been unlawfully taken from the wild, and people who sell or purchase animals without the correct permits risk a fine or court prosecution.
"We have zero tolerance to the illegal trade of wildlife, and make no apology when we issue fines to people who keep native animals without the necessary permits.
"Before buying a native animal as a pet this Christmas, please understand the special care they require, and make sure you have the correct permits."
People can report the illegal trade of wildlife by calling 1300 130 372.
