Jade Perch

From the Barcoo River, Western Queensland

^{Jade Perch (Scortum Barcoo)} Marketed under the name Jade Perch are also produced in large numbers by Ausyfish. We are arguably the largest producer of these fish. Jade Perch is a new species to the developing freshwater fin-fish grow-out sector. Over the last few years this species has been tried by a few people in recirculating systems, and a hand full of pond farmers. These pioneering growers found the Jade Perch growing qualities to be excellent. These early results attracted the attentions of some of Queensland's larger growers who have now tried these fish in their large ponds with some great results. Jade Perch really seem to grow very fast compared to Silver Perch. Some growers have even said, twice as fast.

^{Jade Perch don't handle the colder months, or month for Queensland. The feeding behaviour of Jade Perch is normally vigorous in the extreme. The fish race towards the end of the pond where the approaching farmer is about to feed, creating quite a bow wave as they begin to break the surface with their heads.} 

^{Once they reach the edge of the pond they will extend their entire head from the water in anticipation of a feed. This behaviour decreases in intensity as the temperature drops. We are told by growers, that under 18c surface feeding will almost stop. Some farmers have experienced stock losses during winter. On our farm we were able to harvest fingerlings in water temperatures around 14-15c without losses. The difficulties experienced during winter by these early growers have been overcome through management practices.} 

^{Growers in warmer parts of Australia, especially far north Queensland, should not face these problems at all. It should be noted that Jade Perch are very well suited to grow-out in recirculating systems. They make an excellent beginners species!}

^{Ausyfish produces fingerlings, and egg-sack larvae, and fertilised eggs for customers world-wide. One of the most popular products is egg-sack larvae or fertilised eggs. Click for more information about this product.}

^{This fat is also present in Silver Perch grown in ponds, however Jade Perch have a little more of this fat. Anglers who have caught and eaten these fish from the Barcoo River also report seeing a large “lump” of fat in the gut of the fish. The fish comes from a very hostile environment. Fish in Australian rivers must be able to cope well with the “feast and famine” nature of the rivers systems in this country. After flooding the natural food supply for these fish is abundant. This glut of food is a contrast in the extreme compared to a drought situation where the fish will find getting a feed very difficult. Also during winter (usually the dry season) the fish are relatively inactive and probably rarely feed.}  

^{The stored fat will be used to help the fish survive in these situations. In aquaculture, fish are grown in an artificial environment such as a commercial fish pond or a recirculating system. They are in fact being kept in a “feast” situation. The fish grow rapidly and store fat as quick as they can, to be ready for the “famine”, which never comes.  If your market finds this fat undesirable, perhaps a low protein, low fat, diet and a reduction in food will reduce the level of fat produced by your crop of fish.} 

^{It is our belief that a reduction in the frequency of feeds will also help. Reducing the food while the temperature is high should result in the fish burning up its fat reserves. Probably the optimal temperature for growing this fish is around 27C. Once the fish reaches your desired market weight try keeping the temperature up while reducing the feed intake. For every 10 degrees Centigrade the fishes metabolic rate is doubled. Therefore they burn up energy at twice the rate. You should also be aware that the fishes need for oxygen is also doubled.}  

^{The Jade Perch will grow on a wide variety of diets. Omega-3 content of the flesh varies with the diet used.}

^{When you look at the shapes of the two perch you will notice that the Jade Perch is a very deep-bodied fish compared to a Silver Perch. (See the picture of the two Perches together.) This "deep body" shape is not usually found in wild fish. In fact we have never seen a fish from the natural environment with this shape. The deep body-shape is found in well-feed pond  cultured fish.}

^{The shape has been described (by one of our partners, Alan Sambell), as being, "PLATE FRIENDLY". In fact a larger fillet will fit on the plate compared to a Silver Perch. A plate sized Silver Perch is usually about 750 gram, a Jade Perch of around one kilo will fit on to a plate. To growers this means a larger fish may be sold. Growing a fish to 500 grams is much more of a task than adding a few hundred grams to a fish that is already 500 grams.}

^{The marketing name of Jade Perch was chosen because of the distinctive greenish colour displayed by the fish as the light catches the scales. Barcoo Grunter does not sound as pleasant as Jade Perch. Jade Perch also fits in nicely with the names of our other freshwater Australian native table fish. We already have Silver Perch and Golden Perch. Jade also suggests something of value, and valuable they are. They eat very well and have a firmer, slightly flaky flesh than Silver Perch, their omega-3 levels are the highest. They grow extremely fast and will be highly suited to central and northern Queensland coastal districts having moderate sub tropical to tropical temperatures. They are also proving to be a good species for recirculating systems. (Unlike Silver Perch which are very difficult to grow beyond a few hundred grams in a system.)}

^{We predict a great future for this fish.}  

Below are pictures of wild caught Jade Perch showing the variation in the black spots. Some fish have no spots at all. The body colour is dull because of the stress the fish have been exposed to during capture. The body shape is not as deep as aquacultured specimens.

Below left: This is where the Jade Colour is strongest. Note the improved body shape of the aquacultured fish.

Below right: Held up-side-down, the jade colour is easy to see. 

^{We are often asked, "how big do they grow"? But we just don't know yet. In the wild they don't seem to get very big. Probably because of the hostile environment. This monster, on the right, is only 4 years old, 18.5 inches long,  and weighed in at 3.4KG. This fish is not an aquacultured fish. It was grown on natural food in a dam on a fish farm where predators were controlled, and food was plentiful.}

^{WARNING:    There is another fish, the Scortum Hillii, commonly known as the Leathery Grunter. It is called the Leathery Grunter because of its incredibly tough eating quality. These two fish are very difficult for even he trained eye to tell apart ! If you were a grow-out farmer who had spent time and money to grow a fish that turned out to be the wrong species your reputation could be seriously damaged and your product would be worthless. Be sure to purchase your fingerlings from a reputable hatchery. The brood fish should be Scortum Barcoo from the Barcoo River system. This will ensure that you get the "good" eating fish.}  

Pictured right is a Scortum Hillii photographed immediately after capture from the Dawson River.