Speaking about his decision to retire Fleck said "It is extremely disappointing for me to be retiring due to injury. I felt that I still had a lot to offer to the club and was looking forward to another couple of years at Bath Rugby. However, the calf injury was by far the toughest one that I have ever had to deal with".
Bath will have to plan without the influential centre when they return to Leinster for their opening Heineken Cup Pool 5 match on Saturday 22 October.
Bath have streghtened their squad during the summer moths with the new names including David Bory, Michael Stephenson, Peter Short, Pieter Dixon and up and coming Irish fly half Andy Dunne.