Australia’s largest barramundi farm has started trialling black jewfish in what is understood as a world first for aquaculture.
Humpty Doo Barramundi in the Northern Territory is currently home to thousands of juvenile black jewfish bred by researchers at the Darwin Aquaculture Centre (DAC).
The farm’s fish production manager, Jason Clark, said the team were excited to see whether black jewfish would be suitable as an aquaculture species.
“We’ve just shifted them into a cage, which is inside one of our ponds and they’re growing very nicely,” he said.
“They’re up to 300 grams now and doing well.”
The farm produces more than 100 tonnes of barramundi each week, and has now dedicated some of its ponds to the black jewfish trial. (ABC News)
Mr Clark says there are some key differences between farming jewfish and barramundi, including how they feed.
“A barra is more of a predatory fish with eyes more on the top of their head, whereas these jewfish took a bit longer to come onto the floating feed that we use,” he said.
“They took a bit longer, were a bit slower, but are now finding the feed.
“We’re learning too, though, because as far as we know, this hasn’t been done with this species anywhere in the world and we’re learning lots.”
Swim bladder value
Black jewfish are sought after for their meat and high-value swim bladders, considered a delicacy and aphrodisiac in Asian markets.
The swim bladder, or airbag, is an organ in the fish that regulates its buoyancy. It grows much thicker in black jewfish than in other species.
There has been a growing black-market trade for them in recent years, with the bags selling for up to $1,000 a kilogram.
The swim bladder of a black jewfish can be extremely valuable. (ABC News: Tom Maddocks)
Mr Clark said the potential to farm black jewfish could benefit consumers and the species.
“Farming them like this potentially solves that [black market] and preserves the species in the wild for future generations,” he said.
“We anticipate the growth rates for these fish will be similar to barramundi, and they’ll be ready to harvest in two years.”
Great fish, but also cannibals
Aquaculture researcher Andrea Taylor has been involved in breeding black jewfish at the DAC since 2018.
She said the project had just secured funding from the Cooperative Research Centre for Northern Australia.
It will address knowledge gaps in the fish’s four production stages: broodstock, larval rearing, nursery and grow-out.
Ms Taylor said there was much to learn, including reducing cannibalism.
“We see a fair bit of tail-biting cannibalism in the late-larval and early-juvenile phases, especially if they’re held in high-stocking density,” she said.
“So we think a low-stocking density could be a way to reduce that, but we’ve got trials going now.”
This black jewfish is about four months old. (Supplied: DAC)
Ms Taylor said it was fantastic to see Humpty Doo Barramundi trialling the fish commercially.
“An important part of their grow-out trials will be an assessment of product quality … and what we can expect from a farmed black jewfish and how that might compare to what’s currently being sold in the shops from the commercial wild fishery,” she said.
