Daniel Rawlins landed the Tope Shark 16 miles off the Littlehampton coastline on Tuesday, June 23 at around 8.30pm, following a 30-minute tussle.
It weighed 75lbs and was as almost long as the width of his boat, which was around 6ft 3ins, Daniel claimed.
The 46-year-old from Littlehampton Marina said: "I was jumping up and down, shouting and screaming. It was something very special, the fish of a lifetime."
While it would give you a shock if it swam up next to you, thankfully this species is harmless to humans, according to the Wildlife Trust, feeding on squid and fish.
Daniel and his friend Dennis Tearcey went out on his boat, the Chesil Warrior, to catch bass.
But they changed tack and went out into deeper waters, using mackerel to fish for something bigger.
Suddenly, something yanked on the fishing line, and the fight had begun.
"The rod took off like absolutely crazy. I've caught Tope and sharks all over the world, but this was something else. It was one hell of a fight. Unbelievable."
He added: "Suddenly it popped up to the surface and we realised it was huge. You don't normally see fish that size in Littlehampton."
It was a struggle to get it onto the boat.
Daniel said: "We had to grab it by the tail to get it on board. Dennis tried a couple of times, but kept dropping it. We had one more go - I told him that if we don't get it in now we will lose it.
"Thankfully, he grabbed it and between us we managed to pull it aboard.
"We knew straight away it was close to a record fish."
He added: "I could hardly lift it to be honest."
Once they weighed the fish, they released it back into the water.
According to Daniel, the largest recorded Tope Shark weighed 83lbs and was caught near Portsmouth - so he had the record in his sights.
"Without question, I would like to beat the record and catch a thresher within the next year," he said.
Thresher sharks, which are also common around UK waters, are much larger, weighing up to 750 pounds and with a distinctive long tail, according to the Wildlife Trust.
Daniel, who has been fishing since he was 16, said highlights of his hobby have included fishing off the coast of Kenya, and even catching Great White Sharks.
He said: "I don't believe it will be long before we see a Great White in our waters. It will happen in the next decade because of climate change."