The 20-year-old from the Murray Bushrangers played just one game for the Dockers in 2013, the final round clash against St Kilda when half the side was rested before the finals.
"He's requested a trade but he's a contracted player so we'll just work through the week and see how it goes," said Fremantle's general manager of football, Chris Bond.
Mellington's departure from the Dockers, where he has played just six games in three years would mean the club pretty much struck out with its first three selections at the 2010 NAB AFL National Draft.
Jayden Pitt has retired, Viv Michie has been cruelled by injury and now Mellington wants to be traded. If not for the trade that brought Tendai Mzungu from Gold Coast, where he had been pre-listed, the entire exchange period from that summer would have been a disaster.
Speaking at Etihad Stadium on Monday, Bond was cool on reports that the Dockers might look at former Geelong forward James Podsiadly, but said with nearly three weeks remaining in the Gillette AFL Exchange Period for 2013 nothing could be discounted.
"There's a fair bit of time and still a way to go," he said. "We'll get home and have a look at it from there."
