Research project

Freshwater species - evaluation of sleepy cod and golden perch for aquaculture

Project leader: Brett Herbert
Principal investigator: Peter Graham
Research centre: Freshwater Fisheries and Aquaculture Centre (FFAC) Walkamin
Funding body: DPI&F
Dates: June 1998 - June 2003

Project description

Sleepy cod (Oxyeleotris lineolatus) is a native, tropical species of fish, which is closely related to the highest valued freshwater fish in Asia. It also fetches high prices in Australian markets, about $26-27/kg. Little is known about growth rates or culture methods for sleepy cod, and it is the aim of this project to define the techniques and methods necessary for successful growout. Breeding biology, egg rearing methods, growout in intensive (tank, cage) and extensive (pond) systems, shelter provision in ponds, disease management, and evaluation of diets are being studied. Additionally, there is a bright orange colour variety of this fish, which has high potential for either food and/or as an aquarium fish. Development of a breeding line from orange broodstock will allow determination of whether the orange colour form is genetically or environmentally determined, and thus permit further development if it as an aquaculture product.

Golden perch (Macquaria ambigua) are a native perch, which is widely distributed across inland Australia. There is an established market for large volumes of wild caught fish (about 20 t per month), primarily from western New South Wales. This fishery is to be shut down. Prices of wild caught fish averaged at $11-12/kg in 1999. Golden perch have not been produced in managed aquaculture systems to date, due to inability to wean them on to artificial fish foods. The project aims to develop reliable weaning techniques, to get golden perch eating commercial diets; develop protocols for introduction of weaned golden perch fingerlings into pond growout systems; and to determine methods for growout of golden perch in ponds (densities, feeding regimes etc.)

Achievements

Sleepy cod

Breeding biology and fecundity have been studied, and it has been found that females can produce up to 200000 eggs every two weeks while temperatures are above 25°C. Eggs can successfully be collected and hatched in static water tanks with appropriate management, for stocking into plankton ponds for growout to fingerlings. Fingerling production at Walkamin has been ample, more than enough for on station and off station trials.

Growout trials in ponds indicated that shelter provision does not influence growth rates and size frequency distribution. Laboratory trials found that diets with a lower oil content (to 5%) are superior to higher energy diets in terms of growth and health of the fish.

Pond growout trials have indicated that growth is slower than other tropical species, with only about 20% of fish reaching over 150 g in 14 months. Cage and tank trials indicated more rapid growth rates and more even growth, with one commercial operator reporting 100% of fish over 300 g in 14 months, and 30% over 600 g. Disease problems with bacterial and fungal infections have been overcome with development of handling and prophylactic techniques. Taste trials by a seafood consultant confirmed the high culinary value of sleepy cod, especially the absence of muddy taints (in unpurged fish) common to other freshwater fish. A collaborative project with the Queensland University of Technology, on population genetics of sleepy cod, found the southern strain of sleepy cod from the Fitzroy River to be significantly different to the northern strain. Southern strain sleepy cod appear to be faster growing than the northern strain, and high density culture in cages of tanks appears to improve growth rates and evenness of growth.  There is some production in recirculation systems in southern Queeenland, New South Wales and South Australia.  Prices are over $20/kg for whole fish. This project was disconitunued in 2001 due to lack of funding, although some collaborative work is still ongoing.

Publications are as follows:

Herbert, B.W., Graham, P.A. and Foster, S.D. 2003. Effects of added shelter and stocking density on growth of sleepy cod Oxyeleotris lineolatus in ponds. Journal of the World Aquaculture Socierty 34(4): 433-441.

Herbert, B. and Graham, P. 2004. Breeding and fecundity of the endemic Australian gudgeon, sleepy cod Oxyeleotris lineolatus (Steindachner 1867) (eleotridae). Aquaculture 236: 241-252

Mosiq, J. 2002. Research on Sleepy Cod up north. Austasia Aquaculture 16(1): 30-37.

Herbert, B. 1998. New Aquaculture prospects Aquaculture News 12:1.

Golden Perch

A reliable weaning technique for golden perch has been developed, using frozen plankton or Artemia, and achieving successful weaning over a four week period. Trials using commercially available fresh food for weaning (fish, prawn, scallop etc.) were unsuccessful. Additional trials using a shorter weaning period and different methods have not been successful either. Fish successfully weaned have been used in pond growout trials, and market assessment of pond produced fish has indicated that golden perch need to be of 600-700 g, but were aceptable from 350g. Best prices were for fish from 450-900g. In pond purging for four days produced product of excellent quality, however this would have to be managed case by case as individual ponds can produce off flavours in fish. . The transition from tank to pond has been successful and first trials had >95% survival in all ponds. We compared moist and dry diets, and found that moist diets produced less growth than dry diets, probably due to the 30% moisture content. Fish did feed much better on the moist diets.

Improvements on pond growout techniques have led to about 50% of fish of marketable size after 18 months (from hatching).  Market assessment of pond produced fish has indicated that golden perch need to be of 600-700g, however market studies indicated that good prices ($14-16/kg) could be obtained for smaller fish of 25--350g size. Wholesale prices at the Sydney fish market averaged about $15 for whole fish, competing against a gilled and gutted wild caught product. Colour of fish is important to the market, and using a pale coloured chill bin and harvesting fish from turbid water improved the colour of cultured fish. Pale coloured fish and the golden belly are important to buyers, as these are what is expected from the wild caught fish.

Growth rates were relatively constant throughout the year, but FCR is poorer in warm seasons due to the higher metabolic demands on the fish.  The fish are remarkably tolerant of poor water quality, with high pH being a recurrent issue in growout trials. Better growth rates could be expected in better water quality as found in earthen ponds. Feed quality and development of a feed appropriate for this native fish could give significant improvement in growth rates. After fish reached about 100-200g, growth rates of over 100g per month were achieved in one trial using a diet formulated for Murray cod.

Density trials indicated that golden perch can be successfully grown out in densitites of over 30 000 fish per hectare, with up to three times more fish than that in nursery phase.

Die to changes in departmental priorities and budgets,these trials were supended in June 2003 with final sales of market sized fish in November 2003.

Publications in press are:

Herbert, B. and Graham, P. 2004. Weaning of the golden perch, Macquaria ambigua ambigua, Percicthyidae, onto prepared diets. Journal of Applied Aquaculture 15(3/4):163-171. Austasia Aquaculture .

Herbert, B.W. and Graham, P.A. 2004.Use of Artemia Frozen Zooplankton and Artificial Food for Weaning Fingerlings of the Freshwater Fish Golden Perch Macquaria ambigua ambigua (Percichthyidae). Asian Fisheries Science 16(1).

Graham, P. 2004. Marketing of farmed golden perch. Austasia Aquaculture 18(3):48-49.

Last updated 13 August 2004