Jersey back Aaron Penberthy is leaving the Championship club after three seasons in the Channel Islands.
The 23-year-old ex-Cornish Pirates fly-half has struggled to make Harvey Biljon's starting line-up this year and his contract has not been extended.
Biljon told Penberthy a move to get more game time would be "the best thing at this stage of his career".
He is expected to make his final appearance in the Siam Cup against rivals Guernsey on Saturday, 7 May.
"Decisions like this are part of the nature of professional sport," said head coach Biljon.
"Aaron and I have talked at length about his future, and I have told him that I think the best thing for him is to seek a new challenge where he will get more regular game-time.
"Aaron's made a significant contribution during his time here - the club is grateful for what he's done and wishes him well for the future."