You may not see them, but there are plenty there.
Bull sharks are a common river creature in Queensland's south-east and swim as far up the Brisbane River as Ipswich.
This week, Paul Baleeiro captured up to 20 bull sharks circling from his 22nd floor riverside apartment, in the city's centre.
"I've heard from other people in my building saying that they've seen them before, and I always wanted to see but I thought that the river was a bit muddy to spot them," he said.
"I could see people walking and they didn't see the sharks but I could see them clearly."
It's fantastic footage, but not an unusual occurrence, according to Bonnie Holmes, a lecturer in shark ecology at the University of the Sunshine Coast.
"These guys are there all the time. It's just that, in this particular instance, they've become a little more visible," she said.
"Given that people live in high-rises now and everyone's got a phone or a camera, we're capturing more of these images ... to show people that we do share our waterways and our local areas with these marvellous creatures."
The sight of so many schooling, so visibly, was less common, she said.
"What's unusual is not everybody sees them grouping up like this and there could be several reasons for that. It could be that there's a bunch of food moving through the system.
"We also haven't had any sort of significant rain for a couple of weeks too, so there could be a bit of salt that's pushed up the river as well."
The bull shark is a common river animal, but interactions with them are not, Dr Holmes said.
"Quite often you just won't know that they're there and they won't bother you... it's very rare for for an interaction to actually occur."
