Town would be without a professional keeper if Fettis had not signed, in what is thought to be a loan move with a view to a permanent deal.
Fettis will go straight into the team for the Bournemouth game in the absence of the injured Andy Pettinger and Aidan Davison.
Fettis has just over a year to run on his contract with the Tigers but it is thought to be available on a free transfer after a rumoured bust up with manager Peter Taylor.