McDonald, 26, made a total of nine A-League appearances across his two stints with the Mariners during the 2012/13 and 2015/16 seasons.

Fletcher,24, arrived at the Central Coast Mariners in January 2016 and made seven appearances for the club.

Matthew Fletcher of the Mariners during Round 16

McDonald, a Papua New Guinea international and former Brisbane Roar youth player, paid tribute to the Mariners' players and supporters.

"I would like to thank all of the fans for their support for the club and I wish I could have had the chance to play in front of them this season,” the defender said. 

“The boys are fantastic and I have made a friendship with every single one of them and wish them the brightest and most successful future throughout their careers."

Fletcher, a former youth player with Fulham and Hull City added: “I would like to thank the club, players, staff and fans for everything they have done for me since I started at the Mariners.

“I've met some amazing people that I'll be friends with for the rest of my life and I wish the club all the success in the future."