University of Queensland researchers believe that water quality might play a role in a Brisbane River catfish becoming a world record holder in an electrifying field.
The catfish – which grows up to 1.2 metres long ‑ is known as a longnose, giant salmon-tailed catfish (Plicofollis argyropleuron). It was only rediscovered in the Brisbane River 20 years ago, with the previous last sighting in the 1920s.
Researchers in UQ’s School of Biomedical Sciences and Centre for Marine Science have discovered that this species of catfish has the longest organ used by a non-marine fish in electroreception.
Electroreception is a method of detecting electrical fields used by some sharks, rays and other fish and animals to locate their prey. It is also thought to help fish detect the earth’s magnetic fields, so they can determine the direction in which they are travelling, and to be used in courtship.
Research team member Dr Darryl Whitehead said the species was not a common eating fish in Brisbane, but was found in other Australian regions and the South Pacific as far north as Papua New Guinea, where it was a food staple in smaller island nations.
He said the study published in the Journal of Morphology found that the fish appeared able to adapt their sensory biology to deal with water quality.
“The Brisbane River is a lot saltier than many of the inland streams,” he said.
PhD candidate in the Faculty of Science Mr Arnault Gauthier said that due to the physics of conduction, salt water species were thought to need longer electroreception canals than freshwater species.
Members of the project team have been looking at electrosensory systems of sharks, rays and catfish from a range of habitats to identify factors that optimise the detection of signals.
As part of this investigation the team sampled the longnosed catfish from the University Reach of the Brisbane River.
Mr Gauthier said that documentaries about sharks and rays often mentioned their ability to sense electrical fields using special organs but few people knew that catfish had a similar system.
“This remarkable system allows catfish to detect prey in complete darkness or the murkiest of water, or even prey buried within the sediment.”
Associate Professor Ian Tibbetts of the Centre for Marine Science said he remembered when he first examined this fish.
“I was amazed by a cluster of super-sized pores beneath the eye,” he said.
“Sharks have ampullary pores that are readily seen in a photograph of a shark’s snout, but catfish pores are usually microscopic.”
Media enquiries: Dr Darryl Whitehead (darryl.whitehead@uq.edu.au, +61 7 3365 1929).
