For the first time ever, thousands of Murray cod fingerlings have been released into the river near Murray Bridge to aid the species' long-term survival.
Parents watched on from a boardwalk at the Swanport wetland as children fished the baby cod out of an esky and piffed them into the water.
Most of the 10,000 fingerlings had been released from three boats over the previous hour, as they had become stressed due to a lack of oxygen in their containers.
But involving the children in conservation, organisers hoped, would help them gain an appreciation of the environment.
Perhaps one of them would even be able to catch a mature cod a generation from now.
Community biodiversity officer Glenn Dean, who helped organise the release, hoped as much.
"If we can get a percentage, they will survive, they will breed," he said.
The fingerlings will reportedly grow by as much as 45 centimetres within two years.
The old Murray Bridge corporation built a Murray cod hatchery at the wharf in August of 1972 and released some fingerlings into a riverfront enclosure four months later.
But the fingerlings were either eaten by birds or died of other causes before they could be released into the river, according to historian Ken Wells.
However, released of smaller species such as the Murray hardyhead and purple-spotted gudgeon have taken place since the 2009-10 drought.
Murray Bridge Mayor Brenton Lewis said Sunday's release was another milestone in the story of the Swanport wetland, which had come a long way since 1839, when it was the site of a cattle crossing, and 1866, when the first ferry across the River Murray was built there.
Planting of native vegetation at the wetland began in 1991, the original boardwalks and bird hides came four years later, another loop of more durable walkways was installed in 2003 and a willow-poisoning program went on in 2004.
Over the past several years, toilets and new boardwalks, bird screens and signage have been added.
"There has been ... some serious effort here, serious money invested," Mr Lewis said.
The wetland is located south of the Swanport bridge and can be accessed via the Frank Jackman lookout.