Deformed flathead likely due to genetic mutation, parasite | Photos

INVESTIGATIONS into the two deformed sand flathead caught off Narooma last week leads us to speculate that a genetic mutation or perhaps some form of parasite could be responsible.

Regular visitor Shayne Graham from Wagga and his family caught two strange looking sand flathead out the front of Narooma on the Far South Coast NSW last Tuesday.

His son Ben and wife Kerrie caught the two very odd little fish.

“We weren't too sure if it was a genetic disfiguration or maybe they had contracted a virus at fingerling stage,” he said.

“Aside from the looks both fish were healthy and appeared to be quite normal in all other aspects.  We released both to continue on their amazing little lives!”

The fact that two of these flathead were caught next to each other at the same time remains a real mystery and none of the experts we spoke to could explain it.

Independent marine biologist Julian Pepperell recalls many years ago some sand flathead caught in Jervis Bay with similar bent spines.

“At the time, the Navy was being blamed - high powered sonar, depth charges, you name it - but no conclusions,” he said.

“I've also seen pictures of bream with twisted spines.

“My feeling with these sorts of deformities is that they probably are genetic, or an outside possibility of a parasite or other pathogen affecting bone growth.”

Dr Pepperell said a good fish pathologist could probably answer the latter, if given fresh specimens, but if it's a rare incidence, unlikely that a lab would go to the trouble.

“Best thing would be for anglers to keep an eye out for such fish, freeze them and contact NSW DPI or Australian Museum,” he said.

The Australian Museum has a page dedicated to spinal deformities in fish and looking at the various causes of this phenomenon. Check it out here

Michael McMaster from the Merimbula Aquarium had seen deformities such these in fish twice before, once in a small mulloway and once in a rainbow trout.

His enquiries with a Fisheries officer at the time resulted in him believing it was a genetic disorder that affects the spine and causes the deformity.

A spokesperson for the Department of Primary Industries said the occurrence of such deformities in fish are seen from time to time and can be due to a variety of reasons, as alluded to by Dr Pepperell.

Anglers can report such deformities, with any photos, to the DPI at:

Meanwhile the speculation continues on our social media with humorous references to the deformed fish named Blinky on the Simpsons TV show and even a possible link to the Fukushima nuclear disaster.

If you have any input on this mystery, contact us at

This story Deformed flathead likely due to genetic mutation, parasite first appeared on Narooma News.


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