Sanibel (Fla.) General Employees Retirement System is looking to assign $3 million in active domestic core fixed income to an external firm. The $12 million fund is searching for a manager to run the assets, now in the Florida Municipal Investment Trust. David Lee, director of manager research and principal at Dahab Associates, the funds consultant, said system officials are looking for better returns. A timetable for a selection has not been set, Mr. Lee said. Renee Lynch, the citys finance director, referred questions to Dahab Associates.