The challenge will be held over 36 hours from Friday, with the winning team snagging themselves a $5000 prize.

A catch-photo-release event, the challenge has already attracted more than 60 teams.

The competitors will be hoping to land the biggest Cod during the competition period, which will run from Friday evening through to 8am on Sunday, after which the presentation ceremony will take place.

The dam's water level might be falling - it is now sitting below 30 per cent of capacity - but, according to fisherman Garth Collins, the cod are starting to bite.

"Traditionally from the first frost of the winter on the ground is the time to start fishing for the big cod," Mr Collins said.

"It's a bit of an old fishersman's myth but there's some truth to it.

"There's a lot of action just after dark, during the day is fine, but they really are starting to bite when the sun sets."