The French scrum-half was confirmed as leaving the club earlier this week, and Saints were rumoured to be his ultimate destination.
“Would like to wish Theo Fages all the very best for the future and thank Saints for the Professional way they handled this move,” Koukash tweeted.
Koukash had earlier used Twitter to reveal that more signings for next season for Salford would be confirmed shortly.
“The club is in the process of finalising more signings and will all be announced together next week Wednesday / Thursday . 2 done already,” he said.