But now it is time for the growing smolt to be released into the Otago Harbour, a job more difficult than it might appear.
It will involve a diver positioned in the tank to scoop the agile and slippery fish into buckets, a staff member on a ladder to take the buckets from the diver and a team of school pupils and staff to carry the buckets down the path to the water's edge and release the fish as quickly as possible to minimise stress.
Aquarium manager Tessa Mills said the task, being carried out on September 1, would take about an hour if all went according to plan.
The helpers would be a group of children from the aquarium's education programme.
The salmon were supplied by the Dunedin Community Salmon Trust, which raises, rears and releases salmon smolt into the harbour.
When they mature, the salmon return to local waters to breed, providing recreational anglers with a challenge on their doorstep.
Ms Mills said the tank salmon had been fascinating to watch, sometimes all swimming in one direction until suddenly, at a moment which staff usually missed, all changing their minds and swimming in the opposite direction.
"Sometimes, they swim in two groups in both directions at once ... like a circus act."
