The result extended Chievo's winless run to six matches in Serie A and primavera coach Lorenzo D'Anna will now take charge in an attempt to steer the club he captained as a player away from relegation trouble.
Maran oversaw only two wins since the end of November and the Flying Donkeys sit fourth bottom – two points above SPAL, who occupy the final place in the drop zone.
The 54-year-old joined Chievo in October 2014 and led them to a ninth-place finish in 2015-16. His contract was due to expire at the end of the season.
In a statement on the club's official website, Chievo thanked Maran for his efforts in previously preserving their top-flight status.
"The protagonist of three salvations in Serie A, with ninth place achieved at the end of the 2015-16 season with 50 points in the standings, he is wished good luck for the rest of his career," the statement read.
SPAL travel to second-bottom Verona in a crunch clash on Sunday.