The extra stock of "takable-sized rainbows" had recently been released at Sullivans dam, the southern reservoir and Tomahawk Lagoon, Fish and Game Otago hatchery manager Ian Hadland said.
It was the first year surplus stock had been released, as the hatchery was usually able to carry the stock through.
The 2-year-old stock needed to be liberated to make space for the yearlings.
"That should be good news for anglers feeling the pinch with high travel costs," Mr Hadland said.
Anglers had been reporting good results with some "real beauties" taken over the past couple of weeks.
Compliance had been good at the reservoirs this season with no offences detected, he said.
Many people were opting to catch and release fish, so they never reached the one fish a day bag limit.
As long as they had a licence and did not use bait, there was not much else to do wrong, Mr Hadland said.
More trout would be released in 15 ponds and reservoirs around Otago in spring.
