A number of native finfish species have been identified as suitable for extensive culture. The following looks at some freshwater species that may have potential for extensive farming on a larger scale.
Golden perch (Macquaria ambiqua)
This is predatory fish naturally found throughout the Murray-Darling Basin (MDB). The fish is thickset, with a brownish olive coloured dorsal surface, changing to light yellow cream on the flanks and ventral side.
The golden perch is carnivorous and feeds on small fish, insects and yabbies. It has been known to grow to 10kg, however is usually caught at between 700g - 3kg. This species is one of four freshwater species targeted by most inland recreational fishers.
Golden perch have a firm white flesh and are of good flavour however off-flavour can still be a problem and the fish should be purged in clean water prior to sale. Golden perch are often reluctant to accept artificial diets, which restricts their intensive culture prospects.
However, fingerlings are readily available from a number of hatcheries and this species shows good potential for extensive culture, provided that an adequate supply of food is available in the dams. Golden perch are able to be extensively cultured at stocking densities of up to 250 fish/ha, and are able to reach edible size after 2-3 years. Some farmers are trialling the intensive culture of golden perch in ponds and tanks.
Eel tailed catfish (Tandanus tandanus)
Eel tailed catfish range naturally throughout the rivers of the Murray-Darling basin. They are similar in appearance to most catfish species, with the exception that their caudal is not forked and is similar to an eel tail.
The catfish is brown-grey in colour, often with a mottled appearance. This species has been known to reach over 7kg, however is usually caught much smaller (1-3kg). Eel tailed catfish are often caught by recreational fishers.
Despite their unusual appearance, eel tailed catfish are of excellent eating quality and are often preferred over other freshwater native fish such as golden perch. The flesh is white and well flavoured.
Eel tailed catfish are rarely seen at seafood retailers. However, it should be noted that the American catfish farming industry provides the basis of a billion-dollar industry, with production in excess of 250,000 tonnes annually. Most of this product is processed for fish fingers and processed fillets.
Eel tailed catfish have not been trialed in intensive conditions, so its potential for intensive aquaculture is relatively unknown. Fingerlings are irregularly available and provided adequate natural food is made available, this species can be stocked at a rate of about 250 fish/ha, and should be marketable within 2-3 years.
Yabbies (Cherax destructor)
Yabbies are a species of freshwater crayfish that have a distribution extending throughout the range of the Murray Darling Basin. Their colour ranges from a pale cream colour to almost black, with bluish claws. This species can grow to 150mm in length. Yabbies are targeted by inland commercial fishers. They are used for consumption and fishing bait.
Yabbies are excellent eating, with the edible meat contained within the tail and claws. Significant amounts of product is sold live through the Sydney Fish Market as well as to local restaurants in regional areas and to a number of other retailers throughout Australia.
There is also an established export market, particularly to Europe and Asia where they are considered a delicacy. It is recognised that considerable potential for expansion exists to export this species overseas.
Yabbies can be cultured in intensive situations, with commercial diets readily available. There is a small intensive yabby-farming sector in NSW. However, large amounts of capital are often required to construct facilities required for intensive culture however yabbies can be grown extensively in farm and irrigation dams with little additional infrastructure required (with the exception of purging/packing facilities).
Due to the yabby’s ability to breed profusely in dams, placing 200-400 adults per 1ha water storage will usually lead to a rapid population increase. Ongoing selective harvesting must be implemented to manage the population.
The omnivorous diet allows yabbies to utilise most food sources available. It is expected that extensive farming of yabbies will continue to expand, as new and larger markets open up.
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