STONEFISH are ugly, scary and highly venomous.

And you've never seen one like this before.

Rebecca Phillips was at a friend's house at Golden Beach when her 14-year-old son called from the beach.

"He told us he caught a huge stonefish," Ms Phillips said.

True to his word, when Ms Phillips and the teen's father arrived, they were faced with a monster.

"I am still shocked," she said.

"It was the biggest stonefish I had ever seen."

The teen was fishing near Military Jetty at Golden Beach and reeled in the 6kg beast.

"It was at least 50cm long. I looked at it and just thought, if you stood on that you would be in a world of hurt."

A second large stonefish was spotted at Caloundra at the weekend by a beach-goer.

Ms Phillips said it was a concern as the area was popular with children, especially with school holidays around the corner.

"They lie in the sand and they literally just look like a rock," she said.

"This one was huge, but even the smaller ones would be very painful.

"It's a reminder to children and their parents to be careful when in the area."

If stung, you should seek medical attention immediately.