Fish & Game officer Matt Osborne said that lucky fish was one of 40 fitted with red tags released into the lakes earlier this month in the Fish for Gold promotion.
"So it's a real nail biter to see whether one of the 1200 anglers who've entered Fish for Gold can hook it by the deadline."
He said it was expected Lake Okataina would continue the trend seen over the last few seasons and produce the largest fish, due to favourable growing conditions and lower angling pressure.
Anglers across in the Auckland/Waikato region have been urged to consider the lower Waikato River as a great trout fishery if the water temperature is still below 19C.
"Trout migrate to the Lower Waikato from all over the Waipa catchment to feed on smelt and other small fish during the spring and early summer," Fisheries manager Dr Adam Daniel said.
"The lower Waikato is one of the most underused stretches of river in the region with great trout fishing in and around Hamilton for both boat and bank anglers."