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Takapuna's Lake Pupuke can now boast trout fishing with its better-known recreational drawcards - feeding ducks, picnics and sailing or paddling small craft.

Yesterday, anglers took the opportunity to enter a competition to catch some of the lake's little-known fish life, their enthusiasm boosted by the release of 500 hatchery-raised rainbow trout.

Winner John Shiota of Pakuranga took home prizes worth $375 for landing the heaviest fish of the day.

It weighed only 900g, but one of the competition organisers, David Symes, said it was an encouraging sign for future angling fun.

The newcomers from Fish & Game NZ's Ngongataha hatchery could grow to 4kg, said Mr Symes, who is president of Trout Unlimited, which ran the competition with North Shore Flyfishers.

They were already big enough to evade the lake's ravenous shag colony and would find plenty to eat in the form of the small fry of the lake's coarse fish - tench, perch, rudd and carp.

Mr Symes said trout need running water to spawn. As no streams enter Lake Pupuke, which is a volcanic crater, trout are released annually and licensed anglers are limited to five a day.

The lake is up to 90m deep and fish can find plenty of oxygenated water even in summer.

Yesterday's competition was aimed at young anglers "to expose them to fly-fishing and get them outdoors away from those PlayStation screens".