Mr Horua said he saw the fish swimming across the Laravale bridge when he and his partner Cheyenne Girdler were waiting with their nine-year-old son Laxon for the road to reopen on Wednesday.

The keen fisherman was without rod or reel so he improvised to snare the mullet in a tee shirt.

"The mullet was swimming around the bridge and I couldn't catch it with my hands, so I asked Laxon to give me his tee shirt and I scooped it up with that," he said.

"We did have fish and chips for dinner, but we put that mullet back in the river so the story had a happy ending for the fish."

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Mr Horua said the family had been checking the floodwater situation at Williams Bridge every hour.

"Laxon was home because school was closed but our two younger children, 4-year-old Harper and 3-year-old Levi, were at day care in Beaudesert," he said.

"We really needed to get through to pick them up. My partner was worried about the kids.

"At one point there was an option to have them brought to us and walk them across but it wasn't safe, so we ended up calling a friend and they stayed in Beaudesert overnight."

Mr Horua said they spent so much time at the flooded section of the Mount Lindesay Highway that they got to know people.

"When I grabbed the mullet, a lady asked if she could take a photo," he said.

"And one guy had been there for almost 24 hours, so we got to meet a few people there."

The NSW town of Tumbarumba experienced a similar situation in October last year, when flash flooding saw trout stranded on the local footy field.