James Poulson/Daily Sitka Sentinel/AP Photo

A Washington man caught a record-breaking fish that could be centuries old.

Henry Liebman, a real estate developer from Seattle, caught the shortracker rockfish 10 miles off the coast of Sitka, Alaska. Its size, experts say, indicates that it could be over 200 years old.

"I think it's just a kick. You know for some people something so old is out of their perspective. So you have fun with it," Liebman told ABC News.

Unlike other species, which stop growing at adulthood, rockfish continue to grow as they age.

"There is a strong correlation between length, age and weight," said Troy Tydingco, an area management biologist for the Alaska Department of Fish and Game. "We have some fish that have been aged upwards of 200 years that have been smaller than this one."

This rockfish weighed a record-breaking 39.8 pounds.

"It's the largest fish ever caught by recreational fishing in Alaska. It's a new state record," said Julie Speegle, a public affairs officer for the National Marine Fisheries Service.

Liebman, who made the catch on June 21, told ABC News he is just happy he caught the rare fish.

"I've been fishing all my life and I went out targeting this species," Liebman told ABC News. "I just wanted to try and catch one because no one fishes for them."

Rockfish typically dwell in the deep ocean, too far below the water surface for sport fisherman to reach them.

"I had to drop a bunch of halibut bait down around 900 feet," Liebman said.

"When I got a bite, I felt it run a little. I thought it was only a halibut at first. But when it came out of the water it's sheer size made me think immediately it was a rockfish. This thing was just huge. It was just ridiculous," Liebman continued.

Scientists will analyze the rockfish later this week to determine its exact age.

"The rockfish's ear bone grows one ring for every year it lives just like a tree would," Speegle explained. "By counting these rings we can determine its exact age."