Battling outback teen Keegan Payne became an instant millionaire after reeling in the prize catch in unique Northern Territory fishing competition

A Northern Territory teenager whose family has gone through some very tough times in recent years has become the first winner of a massive Australian fishing prize. 

Keegan Payne thought the 67-centimetre barramundi he reeled in from the  Katherine River on Sunday would make a nice meal for his family. 

He had no idea what that it was a very special fish, worth $1million to whoever caught it, in a prize that had never previously been won.

The keen fisherman from Katherine was out fishing with his sister and some mates on Sunday morning when he got the best bite of his life. 

'We weren't actually expecting a tagged barra at the time, until my little sister actually asked what it was in the fish,' Mr Payne said. 

When he realised it was tagged and that tag was worth $1million, the 19-year-old said he and his sister were 'freakin' out'. 

'We nearly crashed the boat getting back to the boat ramp.'

His sister Addyson, 11, was first to spot the coloured tag worth a magic million.

'We were sitting down and my brother's rod tipped,' she told the ABC.

'He thought it was a catfish – but it was a barra.

'And they didn't see the tag, but I did, and I said; "What's that sticking out of it?"

'And Keegan turned it around, and was like: "No way, no way."

'He was jumping around, screaming.'

Her brother said: 'It was a pretty good fight, it didn't take more than 10 seconds.' 

Mr Payne is the first person to win the biggest prize in the Northern Territory's annual Million Dollar Fish competition, which is in its ninth season. 

He said the win is life-changing for his family, which suffered the tragic death of one of his brothers in a crash four years ago. 

'This is crazy for us, we're a big family, there's eight of us, this is more money than we could ever ask for. This is just great,' the teenager said. 

'The whole family was shocked – they're all proud of me,' he said.

'It's pretty hard going for us at the moment with money, but now with a million dollars, don't have to complain about it.'

He added that 'I can buy what I want, maybe help dad and mum out with the home loans,' and said the family can now afford to take a holiday and is planning a trip to America. 

Mr Payne also intends to buy a new boat and a car this week.

The NT government said it would guarantee there would be a winner of the competition - which was set up to attract tourists to the Top End in the off season -this year, but did not reveal exactly how that would happen.

The very grateful and humble teenager was a worthy recipient of the massive prize. 

When asked what was the best thing about fishing in the Northern Territory, he answered:  'You can catch a million dollar barra.' 

The Cancer Council also got a cheque for $10,000 thanks to the teenager choosing it as his charity of choice.