Minister for Environment and Conservation Paul Caica made the announcement yesterday to help protect the Congolli fish, which can live in marine as well as fresh water systems.

The fish has not been able to breed for at least three years because of low water levels disconnecting the Lakes and Coorong, separating the male and female fish.

Traditionally adult male and female Congolli separate remain separated for much of the year, with the females normally migrating downstream from the Lakes and Goolwa Channel to the Coorong in July to breed.

It is feared the fish will become extinct if they don’t breed in the next year.

The action comes after a successful trial conducted last week where almost 800 Congolli swam into the lock chamber after the upstream gate was opened.

Mr Caica said the Goolwa Barrage boat lock will now be used as a fish passage in the short-term to provide connectivity for part of the Congolli population in the region.

"The plan is to open the upstream lock gate - which is designed to accommodate boats during normal lake operations by about 50cm late in the afternoon, allowing the Congolli to enter the lock chamber," he said.

"The next morning the upstream gate will be closed and the water level equalised before slightly opening the downstream lock gate. After a few hours, the downstream gate will be closed, and the cycle will start again.

"Using the boat lock as a fish passage means we can avoid handling the fish, which would potentially affect their behaviour.’’

Mr Caica said there will be no need to modify any of the barrage infrastructure and no need to use freshwater from the Goolwa Channel. Any saline water likely to be transferred into the Channel during the process is not expected to have any negative impacts.