A 500-pound goliath grouper gulped a 3-foot-long shark down off the coast of Everglades City, Florida. In this image, a nurse shark (Ginglymostoma cirratum) is seen at the Hol Chan Marine Reserve coral reef in the outskirts of San Pedro village, in Ambergris Cay, Belize, June 7, 2018. PEDRO PARDO/AFP/Getty Images

A group of fishermen watched a massive 500-pound goliath grouper gulp a 3-foot-long shark down off the coast of Everglades City, Florida, last week.

During a fishing trip, one of the men caught a 3-foot shark but when he tried to reel it in, he saw a large shadow of another creature.

Captain Jimmy Wheeler with Everglades Fishing Company who was witnessing the rare sight warned people to watch out as this could “freak them out." The massive creature swam up to the shark, opened its mouth and sucked it in.

“He just sucked it in, I don't remember ever seeing anything this crazy," Michelle Wheeler, a witness told Fox News.

The fishermen struggled to pull the shark out of the grouper's mouth for a few minutes until the fishing line loosened and the fish spit out the shark. They had earlier planned to catch and release the shark.

"That same grouper later swallowed a stingray — or manta ray," Michelle said adding, "Goliath groupers have become a nuisance, according to a lot of fishermen. They're eating everything."

"We snorkel and see they'll just go by a fish and suck it in. They're huge. They didn't get that way from not eating," she said.

Goliath groupers must be immediately returned to the ocean if caught on the fishing line as it is under protected category in Florida since 1990 due to its declining population, and possessing them is strictly prohibited in the state.

According to Florida Fish and Wildlife Conservation Commission (FWC), "Large goliath groupers should be left in the water during release. The skeletal structure of large goliath grouper cannot adequately support their weight out of the water without some type of damage."

The fish could be considered harvested if pulled out of the water as it may sustain internal injury. Goliath groupers that are typically identified by dark striped bodies and large mouths can grow up to 8 feet long and weigh about 800 pounds.

In a similar incident in 2014, a giant grouper snatched up a blacktip shark in just one bite and dragged it into the ocean in Bonita Springs, Florida. Baryl Martin, a spokesperson at the Florida Fish and Wildlife Conservation Commission, told ABC News that groupers are opportunity feeders and eat large preys.

“They can appear anywhere from 10 feet under the water to much deeper,” he said adding that they are not an uncommon sight.