We breed silver perch here at Aquablue Seafoods. We use a variety of broodstock to
give us the best quality offspring possible. We have a selection of genetic bloodlines
that we actual cross to give us the best fingerlings that are robust and fast
We use basically 3 strains of silvers — Murray Stock, Cataract Stock and our
own Aquaculture improved bloodlines. Broodstock fish are held in farm dams through the
year and we just catch fish out of our dams and take them to our hatchery for
breeding. The adult silvers live on a diet of natural food that we supplement with a
feed of specially formulated silver perch pellets. It is essential that we keep our
broodstock fit, healthy and happy and when they are they breed easily and give us good
Silver perch are “summer” breeders and dependent on where you are located will
depend on when they breed. Here at Aquablue we have a very long breeding season due to
the mild conditions. Our breeding season now starts late September and runs through
till the end of March. Each year we are noticing a bit of a change in the breeding
season, it is starting earlier and ending earlier, whether or not you believe in
climate change our fish — whether silver, goldens or bass — with the milder
winters and hotter summers are responding to changes in the climate.
We capture fish from our dams as required and we use a variety of methods to do so.
If we just want a few we may just use fishing lines and a piece of peeled prawn as
bait. If we want a lot then we would seine net the whole dam with a knotless net or
even sometimes we catch them in gill nets.
Once captured they
are taken back to the hatchery for breeding in 1400 litre tanks. Silver Perch are a
schooling fish so large numbers can be bred together. If they are 500 gram fish we may
have 5 female and 5 male fish in the one tank. By having a good number of both males
and females breeding together in the same tank we have a better genetic pool/mix in
that tank's batch.
Generally we catch fish that we need that day. Generally catching them during the
day and then breeding then around 5 to 6 pm that afternoon/evening. Fish are stressed
when captured and handled so we do try to be as gentle as possible and get it over as
fast as possible, this ensures we always have good breeding successes.
We anaesthetise our fish, weigh them and hormone inject them to induce breeding. The
fish are injected with HCG a hormone at a rate of 200 iu/kg of fish; this will induce
them to breed approximately 36 hours after injection. This is why we inject them at
5-6pm so we know they will breed around 5-6am — 36 hours later.
It is only the females that need to be injected to induce spawning but we would also
inject half the males and the other half would not be injected. It’s just a cover all
bases policy we use and seems to work exceptionally well for us.
Once injected they are placed in 1400 litre conical bottom spawning tanks that are
heated to 24ºC and heavily aerated to keep the eggs in suspension. If everything has
gone to plan all the fish will have bred on time and we will check egg numbers in the
tanks and then remove the adult broodstock. They will be returned to the dam and not
be accessed again till next year's breeding season.
As a rule Silver Perch are not a fish that can be hand stripped (you can but not
high fertility rates). If they do not breed naturally themselves you cannot strip
them. As a species they are generally easy to breed so this is not a concern.
The eggs are either left in the breeding tanks to hatch or transferred to larval
incubation tanks for hatching which will start to occur 24 to 28 hours after they are
laid. Not all eggs hatch at the same time and hatching will continue for some time
after up to 4 to 6 hours. Once the eggs hatch we reduce the aeration and keep the
larvae in these tanks until they are ready to feed some 6 days later. These larvae are
then transferred to the fingerling ponds for grow out into fingerlings ready for
The fingerling ponds are prepared for the babies by growing algae and zooplankton
ready for the silver perch larvae to eat. As the larvae grow into fry and then
fingerlings we will supplement their food with artificial food. Starting with a dust
and then on to a No.1 pellet. Some 7 to 9 weeks after they are released into the pond
they are around 40 mm plus in length and ready for sale. The growth in the pond is
dependent on the weather and the amount of fingerlings in the pond.
The fingerlings are drain harvested from the ponds and returned to tanks in the fish
shed. There they will be graded, health checked and treated for any parasites etc. It
is essential that the fish we supply to the public are disease free and very healthy.
We will feed them up a bit and after 6 to 7 days in the tanks they will be ready for
sale to other commercial aquaculture farms or the general public for stocking into farm
dams, ponds and aquariums.