The successful angler, who only wants to be known as Seamus from Turangi, caught the monster fish earlier this week.
Seamus took the whopper catch into the Razza Bar and Bistro in Twizel, donating it to the bar to be taxidermied and hung on the wall.
The Turangi resident wanted the 44.3lb (20.1kg) catch to sit proudly next to the bar's other catches on display - a 38.9lb and a 38.2lb trout.
Seamus hopes his catch will be officially announced as a record. Currently the record is a fish caught in the same canal in 2013 weighing in at 42.1lb (19.1kg).
Razza Bar and Bistro employee Sean Colenso told Stuff "it was the biggest brown trout I have ever seen".
For Seamus' catch to officially break the record, it would need to go through a number of processes and the fisherman would need to come forward and be named.
Central South Island Fish and Game field officer Rhys Adams said the scales would have to be verified.
The Mackenzie canals are known for large fish. Colenso told Stuff he believes there'd be bigger fish in the future, as they sit at the bottom of the river eating food from a salmon farm.