Gibbs administrators decided to dismiss Shawn Siede as the baseball and swim coach.
The move was made this week, Siede said. He will remain as a teacher, but will no longer be a coach at the school because of "insufficient progress" in both sports.
"That's the reason I got in a letter," Siede said. "It's a little tough because I wasn't given any warning. How can I fix something if I don't know it's broken."
Siede has coached the swim team the past five seasons. He said the program has gone from 12 swimmers when he first started to more than 50 and the team was winning nearly half of its meets.
Last year, Siede took over the baseball team. In March, the Gladiators beat St. Petersburg to snap an 83-game losing streak that dated back to 2006.
"I coached two sports that weren't exactly the most popular at the school," Siede said. "I thought we made strides in both."
Siede is the second Gibbs coach to be fired in the past three months. In March, the Gladiators ousted boys basketball coach Chad Johnson after he led the program to its first district title since 1994.
A meeting with parents and Gibbs administrators was held Wednesday to discuss the decision to not bring Siede back as coach.
"I have had great support from parents," Siede said. "I'm still puzzled by the decision."