The summer 2013 Syfy film has since become a cult favorite and a sequel is in the works.
"I was really apprehensive, but as an actor I get my insurance from the Screen Actors Guild ... and you have to make so much every year to get that type 1 insurance," Ziering told ABC News. "Halfway through the script, I said to my wife, 'Honey, I don't know about this.' She didn't miss a beat, she said, 'Look, you're going to have two babies [by] this spring, you need to go to work.'"
The former "Beverly Hills 90210" star said that's when he realized: "'Wow, I am going to have to take one for the team' and I probably would have passed on it. But now it's not just me. I'm providing for a wife and two kids."
Ziering, 49, said he continued to read the screenplay and decided the project, an action movie about sharks caught in tornadoes, could be fun.
"I continued reading the script and saw I got to chainsaw my way out of the belly of a shark and said, 'Hey this may not be so bad,'" the actor said. "I have so much fun doing what I'm doing, I forget sometimes, I do this for a living."
Ziering and his wife Erin, whom he married in 2010, have two daughters -- 2-year-old Mia and 6-month-old Penna. The actor said being a father is "the best role I've ever played."