Establishing a fish farm

AQUACULTURE - Farming fish for an expanding market
Can hardly keep
up with demand
By David Mason-Jones
With the growing demand
for low-fat, healthy meat,
fish farming is an appealing
small farm option. This is
the option chosen by Wayne
and Sandra Clark who own
the Shoalhaven Fish and
Yabbies fish farm just off
the Princes Highway near
Sussex Inlet, NSW.
‘The total area of the farm
is just 16 hectares,’ says
Wayne. ‘Before my Sandra
and myself purchased it
years ago it was just a cattle
paddock and certainly not
large enough to be profitable
as a cattle farm.
‘The opportunity we had to
turn the property into a fish
farm meant that the revenue
streams would be higher
from this small block. Now
we are producing three lines
of native fish products and
these include Silver Perch,
Murray Cod and Yabbies.
‘The Silver Perch and Murray Cod are sold wholesale to
the Sydney market and we
can hardly keep up with the
demand. The Yabbies are
sold as bait to fishing enthusiasts who specialise in fishing for native species in
rivers, dams, lakes and
ponds,’ he says.
Wayne and his wife commenced their fish farming
operation in 2004 and it
took them 18 months to
produce their first yield of
Silver Perch and Murray Cod.
The farm had a number of
characteristics which enabled
the Clarks to efficiently convert it to a fish farm. One of
these was clay soil because
this meant that a number of
nursery ponds and growing
out ponds could be developed.
The next useful aspect was
the availability of freshwater.
The Sussex Inlet area re54 Small FARMS
ceives about 1,000 millimetres to 1200 millimetres of
rainfall per annum as a longterm average. The property
has a creek running through
it from which Wayne and
Sandra have approval to
draw water for the farm fishponds. The creek has a
catchment area of 250
hectares of natural state forest.
A third important characteristic has been the gently
sloping hills on the property
leading down to the creek.
Thishelped when a series of
panels was built allowing
water to drain by gravity to a
settling pond at the lowest
point of the farm.
A fourth characteristic is
the availability of electrical
power from the main grid.
While fish will exist in ponds
without artificial aeration of
the water, they will certainly
not exist in the large numbers required for commercial
production. A reliable electricity supply is therefore
critical in a commercial fish
farm to drive the aeration
machines. ‘I have installed a
transfer on this property that
would be large enough to
run a small suburb,’ says
Wayne.
Since converting the cattle
paddock to a fish farm,
Wayne and Sandra have a total
surface area of 2.4 hectares
under water. The ponds include;
Storage Dam: One large
dam serves as a water collection and storage area. This
dam has a maximum depth
of 5 metres and has a surface
area of half of a hectare. No
fish are grown in the dam it is purely a storage of freshwater.
Nursery/grow out dams:
Ten nursery/grow out dams
have been developed to cater
for the early stages of growth
The reservoir for the collection of fresh water is on
the creek at the entry to the property. The dam has
a 250 hectare natural forest catchment area.
A typical nursery pond. Note the bird mesh to prevent bird predation and the bubblers which keep the
water oxygenated.
Paddlewheel thrashers are efficient and can lift the
fish carrying capacity of the ponds higher than is
possible with the use of bubblers.
January/February 2009
AQUACULTURE - Farming fish for an expanding market
of the fish. Young fish of
around the same age and
weight are seeded into these
ponds and fed daily while
they grow out to a larger size.
Due to the problem of bird
predation all of these ponds
are protected by bird mesh.
All the dams and ponds on
the property have piping to
allow them to be filled from
the storage dam. They are
also all linked by pipe to the
settling pond so that, after
the fish are harvested, the
nutrient rich water in the
nursery/grow out pond can
be drained to the settling
pond. The current method
of oxygenating the water in
the nursery/grow out dams is
by a system of bubblers. Although this is sufficient to
cater for the current level of
fish production, it is a less efJanuary/February 2009
ficient technology than paddlewheel thrashing machines.
Settling pond: A deep settling pond is located low on
the side of the hill on which
the nursery/grow out ponds
have been developed. This
pond is large enough to hold
all water drained from those
ponds. As this water is nutrient rich it is not allowed to
flow back into the natural
water system. Water from
the settling pond, shandied
with water from the storage
dam, is used to refill the
nursery/grow out ponds
when a new batch of fish are
to be grown.
Large grow out pond: In addition to the 10 smaller
nursery grow out ponds
there is a large grow out
pond. This pond is deep
Silver Perch are one of the mainstays of Wayne
Clark’s fish farm.
The Murray Cod is another main product of the
farm. These sell at a farm gate price of around
$18.00 per kilogram.
Small FARMS 55
AQUACULTURE - Farming fish for an expanding market
enough, and muddy enough,
to allow the fish to avoid
bird attack. At the moment
the large grow out pond is
the one which is equipped
with the most efficient paddlewheel to oxygenate the
water. Large numbers of fish
can therefore be held. The
paddle also mixes the water
so there is no cold water in
the lower levels of the pond.
This maintains optimum
growing conditions.
Purging tanks: The farm
currently has two purging
tanks. One is a 4,000 litre
tank for small numbers of
fish and yabbies and the
other, a 30,000 litre tank for
larger quantities of fish.
The role of a purging tank is
to make sure that the digestive tract of the fish or yabbies is cleared of mud and
grit prior to going to market.
Current production: The
current production from the
farm is around 2.5 tonnes of
fish per annum and Wayne’s
target is to lift this to around
10 tonnes per annum. The
main way of achieving this
will not be to develop more
ponds but, rather, to improve the efficiency with
which the water in all ponds
is oxygenated.
The main grow out dam is
currently stocked with
around 1,400 Silver Perch
and these are growing to a
size of
600-700 grams.
Wayne reports that the current farm gate price for his
Perch is around $10 per kilogram.
Murray Cod are currently
selling for around $18 per
kilogram and the other
product of the farm, Yabbies,
sell for around $25 per kilogram. Wayne reports that,
although the yabbies give a
higher per kilogram financial
return, he does not focus on
them because they are more
labour intensive. Yabbies
grow naturally in the ponds
and therefore are treated as a
buy catch and sold to anglers.
Optimum conditions: The
growth rate of fish varies
with the temperature of the
water. In winter the water
temperature is around 9°10°C and this is insufficient
to allow fish growth. The
fish basically go dormant
during this period. In summer the water temperature
rises to an average of 2025°C thus producing optimum growing conditions.
Pond management: Nursery
ponds go through a cycle of
pond management between
periods of production and
fallow periods. When the
fish are harvested from the
nursery ponds, the nutrient
rich water is drained to the
settling pond. The nursery
ponds are then allowed to
dry in the sun until clay at
the base of the pond cracks.
Sunlight kills unwanted
bacteria in the clay pan. The
clay pan is ploughed to allow
further sunlight penetration.
The pond base is treated with
lime to make sure that the
pH level of the water is at the
optimum level the new
batch of fish is introduced.■
Yabbies are a buy-catch of the fish farming operation. While they sell at around $25.00 per kilogram,
they are not the main focus of the farm because
they are very labour intensive.
The farm routine involves daily feeding of all fish in
the nursery and grow out ponds. Specialist fish pellets are purchased for this purpose.
■ Wayne and Sandra Clark,
phone 02 4443 5443.
All of the ponds and dams on the property have waterpipes that give Wayne, pictured, the ability to
drain them or fill them with water from a number of
different sources.
56 Small FARMS
January/February 2009