A rare 6-foot tarpon fish was caught off Chappaquiddick shores by fisherman Richard Mann on Sunday night. 

While tarpons are native to the Atlantic, they typically only swim up to Virginia and hardly come to the Island’s waters. Known as “silver kings” for their glistening scales, they thrive in warm waters, and are Florida’s premier game fish.

“The intended target was bluefish, but this fish had a different plan,” Mr. Mann said.

Mr. Mann, who lives in Halifax, has been coming down to the Island to compete in the annual Martha’s Vineyard Derby every year since 2017.

Phil Horton, the derby chairman, said while it was a remarkable catch, tarpon are not eligible for awards. Derby fishermen are only allowed to compete with bluefish, bonito and false albacore.

Although it wasn’t eligible, Mr. Mann said it was a once in a lifetime catch. 

“I just cast a fresh piece of bait out, and before I could even put the rod down, I felt the fish hit the line,” he said. “ I picked it up, and I went, I know what that is. I know it’s not a small bluefish. I know it’s something much bigger with teeth.”

It was dark outside but Mr. Mann said he could see a 6-foot tall splash in the moonlight when the tarpon jumped out of the water in a 30-minute battle. His friends came to help him during the fight.

“We just thought it was a shark, you know, thrashing around in the water,” he said.

Eventually, Mr. Mann’s derby partner, Buddy D’Agostino, got a hold of the tarpon’s tail and his brother, Tony, grabbed the mouth.

“We were all hooting and hollering and in shock,” Mr. Mann said. “We couldn’t believe what we just did.”

The tarpon was too big to hold, so Mr. Mann and his friends knelt down and tipped it onto its side to take a picture. They quickly measured it before throwing it back in the water. Mr. Mann said the tarpon was a little stunned at first, but then quickly swam off. 

Afterwards, Mr. Mann and his friends packed-up their gear and went to cook a celebratory meal.

“To catch it on the first night of the derby was hilarious to me,” he said.