Five of the 13 wins that Simon Grayson oversaw came from 22 games this season.
The defeat by Oxford United left the club 22nd in the League One table, and that's where Simon Grayson left the club immediately.
The Cod Army lost to the U's for the fifth time in six league games.
The assistant to the 51-year-old will leave the club.
Everyone at the club would like to say thanks to Simon and David for their hard work and professionalism.
Joey Barton left the club after almost three years in charge, but he was replaced by Simon Grayson.
It was the first job for the former boss since he was fired.
After initially joining until the end of the 2020-21 season, he signed a new "long-term" deal in March and steered them to a mid-table finish.
The club has struggled this season, losing their first four games of the campaign before their current run began.
Their most recent victory was against fellow strugglers Crewe and they will be going to AFC Wimbledon on Saturday.
