Breeding Information

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 growing.

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 progeny.

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 sale.

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.