Warrandyte's Nathan Vernon took home $2000 for catching a tagged brown trout in the Mitta Mitta River on a grasshopper pattern dry fly.
Nathan won the money as part of the Victorian Government's Golden Tag competition.
He was fishing with fellow winner Joseph White, from Fitzroy, over the Labour Day long weekend and snagged the trout about an hour after Joseph caught his.
The duo only realised they had both won after seeing the winner tag on the second fish.
Nathan will use the money to buy a new fly fishing rod.