Ian was helping with a stingray tagging program in Thailand when he discovered the enormous specimen deep in the Maeklong River and used a Snake head fish as bait to snare it.
“It dragged me across the boat and would have pulled me in had my colleague not grabbed my trousers - it was like the whole earth had just moved. I knew it was going to a big one," the 45-year-old said.
"It buried itself on the bottom and the main fight was trying to get it off the floor.
"I tried with every ounce of power but it just would not budge. After half an hour my arms began shaking and after an hour my legs went.
"Another 30 minutes went by and then I put a glove on and physically pulled the line with gritted teeth and somehow I found the reserves to shift the fish."