Lee Edmond-Hiett, 43, from Southampton, was fishing near the White Swan on Sunday when he landed the mammoth 16lb 8oz barbel in his first attempt targeting the species.
Using a cheesy garlic dumbbell, he managed to catch the impressive freshwater fish.
Lee, a senior facilities manager for Mitie, said: “I was gobsmacked to be honest. I was shaking like a leaf.
“It was such a great fight. Pound for pound, they are one of the hardest-fighting freshwater fish.
“I am over the moon, it’s brilliant.”
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The river was reportedly “very low,” and there were only a handful of fishable spots.
After a couple of fruitless hours he got a bite and the fish nearly pulled his rod into the water.
With help from another local angler, a stranger, he was able to land the fish which barely fit into his net.
He said: “I was fishing for about two hours before that. It was my first bite.
“Anything over 15 pounds is a fish of a lifetime.
“I have always wanted to catch one. Knowing it’s one of the best fighting fish from a river.
“It is not an easy fish to catch.”
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Still “buzzing” from the experience, he encouraged others to try barbel fishing, stating that many people don’t realise these “monster specimens” live in the river.
He then returned the fish to the water after taking a quick photograph with his catch.
Lee has been fishing since he was ten years old, and still tries to go fishing a couple of times a month.
He added: “I don’t think I am going to beat that one, to be honest. That was the one I was targeting down there.”
The website Barbel Fishing World features a list of validated barbel catch records by river. According to its list, the record for the largest barbel caught in the River Itchen is 16lb and 10oz, landed by Terry Lathwell in 2017.
The current British barbel record was set by Colin Smithson on November 7, 2019, weighing 21lb 2oz.