EVER wonder what happens below the water's surface?

You're not alone, that's why researchers have developed the tagging system and the first two tagged barramundi have been caught in Lake Monduran.

Lake Monduran's Sponsor a Barra Inc founder Julie Whalley said Sharyn Smith caught the first tagged barramundi in the lake when she was up on a day fish from Maroochydore.

The barramundi has had an "unreal” growth rate in the past year. When it was released it was 18.5cm and was 59cm when measured upon capture.

The Sponsor a Barra tag belonged to Wayne Jones.

"It's always a good fight with barra,” Ms Smith said.

"We'd like to fish there all the time, but we try to get up there once a month.”

Ms Smith said she thought tagging was an excellent idea because it let people know that there were fish to be caught.

"I caught four when we were up for the day,” she said.

"There's definitely some big fish in there, because we have been busted off quite a few times.”

Bill Sawynok, from Suntag Australia, said tagging was important as it was one of the cheapest ways of monitoring fish that had been stocked as tagging was carried out by volunteers.

"Tagging is also important to track fish within the impoundments and more importantly to track them when the dam spills and allows the fish to escape,” he said.

"In 2011 when Awoonga spilled it was estimated that around 30,000 barramundi escaped from the dam. Tagged fish from Awoonga were later caught as far north as Townsville and as far south as the Burnett River.”

Ms Whalley said Sponsor a Barra had released 120 and would be doing a tagged run of barramundi in October.

"There are people who tag and release fish when they catch them but there is no record of those,” she said.

As there's only been three recaptures of tagged fish in Lake Monduran to date, there is not sufficient data to indicate an exact growth and movement in the lake. However, Mr Sawynok predicted the growth rate would be about 150-200mm a year in the first few years and then it would slow down. If you would like your name on a tag, donate $20 and contact Ms Whalley at sponsorabarra@gmail.com.