In Queensland, Barramundi occur naturally from the Mary River in south east Queensland to the Gulf of Carpentaria. There has been considerable interest in this species as a farmed table fish. They have demonstrated their suitability for growing in Recirculating Aquaculture Systems (RAS) as well as in open ponds. Over recent years cage culture of this species has also shown considerable promise. A significant Barramundi grow-out industry has now developed in Australia.
There are three distinct strains of golden perch. The Murray/Darling River system, the Lake Eyre Drainage System, and the Fitzroy/Dawson River System. The largest is the Murray Darling System, (Marked in blue, see map below.) which extends over four states. Starting in Queensland moving through New South Wales and Victoria and finally reaching the sea in South Australia. The Lake Eyre System, (red) also drains from Queensland to South Australia where it empties into Lake Eyre and finally just dries up! The Fitzroy Dawson River system, (yellow) is limited to Queensland. It drains a large portion of Central Queensland and empties into the sea at Rockhampton. There has been some debate over which of these strains of golden perch may be best for aquaculture. Some say the colour is the most important factor and that one strain or the other displays the most "gold" colour. The first commercial supplies of golden perch fingerlings were supplied to grow-out farms in Australia during the 2003-4 season. They were from the Lake Eyre strain. These fish have shown excellent growth. One grower reports that they grow much faster than silver perch. This grower is using large round Polly tanks. In his words the fish are described as "..the barramundi of the inland..".
Murray Cod have developed a reputation as being very suitable for growing in RAS. A well operated, quality RAS can produce a fish of around 800gms in about 8-10 months.
Due to their popularity as an angling species and the success of the stocking programs in Queensland competition for fingerlings between the two sectors has resulted in a shortage of fingerlings in some years. Therefore the advance ordering of fingerlings from hatcheries is recommended.
Jade Perch (Scortum barcoo)
This species has developed in to an important new aquaculture species in Australia. It has also found acceptance in a number of other countries, especially throughout Asia. It's extraordinarily high omega-3 levels has made it a popular table fish in these countries.
The “Jade” colour is along the top of the fish.
They grow well in reticulating systems and ponds. They hate the cold, but love the heat. Therefore, for out-door pond production, they are probably only suitable for tropical or sub-tropical climates. Seemingly, they have a much higher metabolic rate, therefore to avoid water quality problems should be stocked at a much lower rate than Silver perch. They feed eagerly on anything you might throw in to ponds.
They have a high fat content, the good kind, "the good oil, omega-3" However if you grow these fish, and this is not a "quality" you desire, then a low protein diet will reduce the fat content. Of course this should represent a saving on your feed bill too. The flesh it self is similar to that of Silver perch, perhaps just a little firmer.
Live shipping is different in some ways to Silver perch. Consideration should be given to the differences mentioned above. Fingerlings are readily available from members who have hatcheries. (See members lists)
One of the most promising fish for future aquaculture. This fish has many qualities to give it all-round appeal as a major aquaculture species for the future. It has been argued that this species has the best eating quality of all Australian freshwater fish, extremely easy to transport and at high densities, with a high flesh recovery.
Once past the smaller fingerling stages, when cannibalism is a real problem, the fish can be kept and grown in high densities. Early indications are that it will be unsuitable for pond grow-out situations, however will probably be ideal for growing in Recirculating Aquaculture Systems (RAS). Work is now underway to answer some of the questions we need to ask. Will they take to artificial feeds? How fast do they grow? Just how densely can they be stocked? Among others these questions have to be asked. However there are a few smaller growers who have already tried these fish for themselves with positive result. These growers have not had the benefit of having a blue print to follow.
In Asia there already exists a fish very similar to our Sleepy Cod. This fish fetches some of the highest prices, (around four times that of Silver perch) and is regarded as top quality. There is no doubt an overseas market is out there just waiting for someone to meet. Shipping live, market sized Sleepy Cod, should prove to be relatively unchallenging. They do seem to live up to their name and lay motionless in shipping bags. This means their use of oxygen is minimal and therefore production of CO2 low. Many large fish should be able to be packed in an absolute minimum amount of water.
Experienced hatcheries have no difficulty producing fingerlings, however they are one of the more time consuming to produce and therefore are a little more expensive. If you intend to purchase fingerlings they should be ordered well before the season begins to avoid disappointment.
Silver Perch Strike Oil
In 1998 the CSIRO completed a study on the beneficial oils that are found in Australian fish. The results of this study will give a real boost to the marketing of Silver Perch. Most of us have known that Silver Perch contain a high level of omega-3 fatty acids. What we did not know was how this compared to other sea-foods and aquaculture products. Well the news could not have been better, when compared with around 200 other products in this category Silver Perch come in a very good third. Now all we need is a few hundred ton to sell to all the people who want to live longer.
Number one was the Swordfish, the one the game fisherman go after. Not much chance we’ll have too much competition from this one! This fish has a massive 1,667 milligrams of the good oil to every 100 grams.
Number two is the Atlantic Salmon. This is the same one that’s being farmed in South Australia. The product is usually targeted at the Asian market, particularly Japan. In my option no real competition will come from this area as the overseas markets usually bring prices that would make the domestic market look like a poor hobby! This fish has 842 milligrams per 100 grams.
Now we get to the real "good oil" Silver Perch. Easy to farm, easy to handle, easy to... well you know that stuff already. But what about this omega-3 oil business? Well the CSIRO study has revealed that our very own Silver Perch has 792 milligrams per 100 grams of the "good oil."
Yes that is very high indeed, lets compare this with a few of our competitive products. These are figures from the CSIRO study that will show just how well Silver Perch compares. What about the good old Rainbow Trout, been farmed for a long time in Australian, but only 448 mg/100g, a big drop from Silver Perch. The Brown Trout has even less at only 415mg/100g. There’s been a lot of interest in our slippery friends the Eels, but not much of this omega-3 stuff, 313mg/100g. Now our real competition might well come from our friends in the Barramundi grow-out business. But not if omega-3 is used as a marketing tool! Barra grown in freshwater have 206mg/100g, and Barra grown in sea water have 150mg/100g.
Not even alternative products such as chicken, beef and lamb have anywhere near the levels of omega-3. Silver Perch has 10 to 100 times more omega-3 than these more traditional food products. While we are on the subject of the more traditional meats, did you know your local butcher can sell your Silver Perch as an alternative product. With a few minor requirements he is able to sell Silver Perch from your farm. (check with health dept. and local council)
What about this stuff (omega-3) anyway? What’s so good about it? Well it seems it really can help you live longer. It has benefits to human blood vessels, helps protect against heart rhythm disorders, may even help protect against some forms of cancer, (wish I knew that before). But the list goes on, infants brain and retina function and development my also benefit, as well as reduce coronary heart disease, high blood pressure and rheumatoid arthritis. Silver Perch also contains lower levels of cholesterol than chicken, beef and lamb!
Here are some quotes from the CSIRO:
"the unique nutritional benefits of marine oils come from the effects of their long chain omega-3 polyunsaturated fatty acids, and particularly DHA and EPA.
"the body can only make small amounts of these fatty acids. and therefore we rely on dietary sources...
" Australian fish have higher levels of the beneficial fatty acid DHA than fish from northern hemisphere waters.
"Other beneficial oils present in seafood (a term which includes farmed fish ...) include omega-6AA which is important for growth and seems to play a role in our general good health and well-being."
IF SILVER PERCH WAS A PILL IT WOULD BE WORTH MORE THAN VIAGRA!
Omega 3 found in the Silver Perch...
Reduces Aggression You are less likely to express stress-induced aggression if your brain is under the influence of fish oil, according to Japanese researchers. In a new double-blind test of 41 adult students, those taking 1.5 to 1.8 daily grams of DHA fish oil for three months did not become more socially aggressive at a time of severe mental stress: final exams. In contrast, students taking a dummy look-alike capsule showed significant jumps in social aggression, as measured by psychological tests. This effect on stress may help explain how fish oil prevents heart disease. Stress hormones triggered by hostility and anger can constrict arteries and accelerate the formation of blockages, research shows; fish oil may suppress the release of those hormones.
Stimulates young minds Foetuses and infants must get sufficient omega-3 oils for optimal brain development, says William Connor, Oregon Health Sciences University. In one telling study of premature infants, those fed breast milk had 8 points higher I.Q. at age 8 than those fed standard infant formula. Connor credits breast milk's higher amounts of DHA for that superior intelligence. In infant rhesus monkeys deprived of omega-3-type oils, Connor found severely impaired visual acuity and behaviour indicative of a neurological defect. Autopsies revealed abnormalities in brain cells. Connor advises pregnant women to eat fish a couple of times a week, especially during the last trimester, the time of greatest foetal brain growth. And breast feeding is preferable to infant formula, he says.
Blunts Brain Damage? Fish oil may eventually be proved to lessen alcohol-induced brain damage, Salem says. He explains that excessive alcohol depletes brain levels of omega-3's -- DHA in particular -- which leads to neurological damage and impaired vision. He put experimental animals on high-alcohol, low omega-3 diets for six months to three years. They suffered severe losses of DHA in brain cells and detrimental changes in brain functioning. Some scientists speculate that fish oil also may have a protective role in degenerative brain diseases leading to memory loss and dementia. The brains of deceased Alzheimer's sufferers, for example, show low levels of omega-3 fats.
Food for thought?!
(Re printed from: AAQ Newsletter December 1998 and March 1999 by, Bruce Sambell)