Aquaponics

Aquaponics combines Aquaculture and Hydroponics to very efficiently grow fish and plants. Aquaponics are growing in popularity, particularly with hobbyists, and with good reason- fresh fish and vegetables grown in your backyard is a great way to be self sufficient.

There is plenty of information available about aquaponics systems and setups- information about suitable fish for your aquaponic system will be presented here.

Before stocking your aquaponic system, it is important to fill and run the tank to ensure that there are no leaks and the syphons work, etc. Once this is done, run the system for at least a week with all the grow media installed and pumps running, etc. This allows the system to establish bacteria and the water parameters to settle.

If you have access to water test kits, test your pH, Ammonia, hardness and Temperature morning and night. Log the results for a week to establish a baseline trend in your water quality and to assess whether further treatment is necessary and when fish can be safely stocked.

Fingerling Availability

Availability of fingerlings to stock your newly setup aquaponic system is seasonal.

Jade Perch- Late November – June. - Peak January – March

Silver Perch- December – August  - Peak January – March

Murray Cod – January – March  Peak – February

Barramundi – January – March  Peak – February

Sleepy Cod - January – March  Peak – February

Fingerling supply through the season can be variable as we may be between batches. It is important to consider the seasonal supply of fingerlings when you are looking at setting up your aquaponic system.

Species Selection

Many species are suitable for aquaponics, and they are normally proven performers in intensive aquaculture. Species for aquaponics need to be able to handle the artificial tank environment, be held at density and accept and grow on a commercial pellet.  Some popular choices are-

Jade Perch

Jade Perch make excellent candidates for Aquaponics. They are hardy, grow fast and taste good on the plate. Jade Perch have the highest level of Omega 3 oils in any seafood available in Australia. (CSIRO, 1998).

Jades readily accept pellets and do well on a low protein, high fibre diet. They are aggressive feeders, and care should be taken to ensure that all the fish in the tank get fed, not just the dominant fish in the population. This will help to ensure even growth.

Jade Perch perform best in water 6.5-8.0 pH, nil ammonia, hardness >80ppm, and temperature 18-32C.

Jades are one of the better growth performers in aquaculture- they can obtain a plate size of 500g in under 12 months (in SE Queensland), if conditions are suitable. Plate size in 18 months is more common and would be what is expected for most aquaponic systems. They can grow to 50cm and 8kg!

The biggest issue with Jade Perch is temperature. Jades stop metabolizing food at water temperatures below 18C, and will start to show stress at 16C, and death at prolonged periods below 14C. During winter, it is important to keep water temperatures above 16C.  Jades are susceptible to common diseases that affect most cultured fish, but bacterial and fungal problems are most prevalent in the cooler temperatures, and ectoparasites during the spring and autumn. Most of these health issues can be avoided if water quality is kept at a optimum level and water temperature is maintained above 22C.

Jades have a firm, white flesh with a oily texture. They present excellently smoked, but can also be grilled, baked or steamed. Frying this fish can make the fish too oily. They take up flavours well and are great used as a base in Asian style dishes.

 

Silver Perch

Silver Perch also make excellent aquaponic subjects. They are very hardy, and will tolerate water conditions that would kill many other species. They make excellent starter fish if you have not kept fish before.

Ideal water parameters are- pH- 6.5-8.0, Ammonia nil, Hardness > 80ppm and temperature12-26C. Silvers tolerate the extremes of water temperatures better than almost any other aquacultured fish in Australia, and will grow through about 9 months of the year in SEQ.

Silvers main disadvantage is their slow growth. To get the fish to a plate size of 500-600g, take 24 months up too 3 years. This is a long time to maintain and feed the fish in a captive environment.

Silvers will readily accept pellets and do best on a diet similar to Jade Perch- a low protein, high fibre diet.

Silvers generally do not suffer from any major health issues.

Silver Perch are a good eating fish, with firm white flesh and a delicate flavor. They are great steamed, grilled, fried or used as a base in Asian Dishes.

Murray Cod

Murray Cod are Australia's biggest freshwater fish and have long been a staple in the commercial aquaculture industry. Murray Cod are more difficult to keep than the Silver and Jade Perch, largely due to their aggressive nature and their susceptibility to health problems.

Ideal Water parameters for Murray Cod- pH- 7.0-8.0, Ammonia- Nil, Hardness >100 ppm and temperature 12-26C. Murray Cod grow well at 18-22C, but are susceptible to bacterial and fungal issues when water temperatures get over 26C.

Murray Cod are carnivorous in nature, and require a high protein diet. They can be a little difficult to feed, and often take some training to get them to readily accept a pellet. They can get to a plate size of 600-800g in 18 months, but 24 months is more common.

One big disadvantage with Murray Cod is their aggressive behavior towards their tankmates. They are territorial by nature, and will cannibalize. It is important to ensure that all the fish in the tank are offered the opportunity to feed to ensure that not just the dominant fish get fed. Cod will often spar and damage themselves as a result, leaving a area for bacterial and fungal infection. It is important to grade this fish and keep fish of a similar size together to limit the aggressive behavior as much as possible. For this reason, it is often necessary to separate the dominant fish in a tank and so several culture tanks may be necessary.  

Murray Cod have firm, white flesh and provide a chunky fillet. They have a good, distinct flavour, and lend themselves to all the common cooking methods.

Barramundi

Barramundi are the most popular fish for Aquaponics, but are not always a good choice as they are a tropical species and require heating and can be aggressive to each other.

Barramundi can be delicate subjects, not tolerating poor water conditions or husbandry.

Ideal Water parameters – pH- 7.0-8.5, Ammonia – Nil, Hardness > 100ppm and Temperature 25C+. They do not metabolize food below 18C, stress at 16C and prolonged exposure below 15C will result in death.

Barramundi will readily accept a pellet, and can be aggressive feeders, preferring to take pellets from the surface. They are carnivorous in nature, and require a high protein diet.

They are territorial, and will cannibalize. It is important to ensure that all the fish in the tank are offered the opportunity to feed to ensure that not just the dominant fish get fed. It is important to grade this fish and keep fish of a similar size together to limit the aggressive behavior as much as possible. For this reason, it is often necessary to separate the larger fish in a tank and so several culture tanks may be necessary.  

 

 

Sleepy Cod

Sleepy Cod are not well known as aquaculture species, and despite their appearance are excellent eating. They are a tropical species and can be difficult to feed.

Ideal Water Parameters-  pH- 7.0-8.5, Ammonia – Nil, Hardness > 100ppm and Temperature 25C+. They do not metabolize food below 18C, and stress at 16C prolonged exposure below 16C can result in death.

They will accept a pellet, although can be frustrating to feed, often requiring several small feeds a day to ensure that all are fed. They do best on a sinking pellet. They are carnivorous, and so do best on a high protein diet. Sleepy Cod are considered plate size at 600g+, and due to their body structure, quite small fillets come off a 600g fish. Most Sleepies are presented at 800g-1kg commercially. They can obtain 600g in 18 months if conditions are suitable.

Sleepy Cod present excellently on the table, and have one of the best tasting flesh for a saltwater fish. They lend themselves to all the common methods of cooking.

Feeding

All the species mentioned above accept commercial fish food pellets. These pellets are a complete diet specifically manufactured to meet the nutritional and growth requirements of the fish. No further supplemental food is necessary. Pellets are available in 1mm, 2mm, 3mm, 4mm, 5mm, 6mm sizes and mostly in the floating type. Sinking Pellets are available but are not always stocked. It is important to feed fish the right size pellet, although keep in mind that a larger fish can eat a small pellet but a small fish can’t eat a large pellet.

Feed is available in the following sizes and prices-

Crumble- 2kg Bag $16

1mm Pellet- 2kg Bag $16

2,3,4,6mm Pellets- 4kg Bucket $30

Courier is available on food for $12-15 depending on your location and amount ordered.

When feeding your fish, a general rule is too feed as much as they can eat in 2-3 minutes. This amount will change as the fish grow and the water temperature changes. If after 3 minutes there is uneaten food in the tank, the fish have probably been fed too much and it is best to remove it before it pollutes the tank.

Husbandry and stocking rates

We recommend stocking your aquaponic system at no more than 1 fish per 10L/ water, assuming that you have adequate filtration to process the fish waste. Remember the plants are mostly absorbing Nitrates which is the end product of nitrification, so the wastes need to be processed by bacteria in a filter medium, whether it be a aquaculture filter or your grow bed.

Good general husbandry involves feeding your fish daily, observing their behavior, and testing the water if their behavior is abnormal. Fish going off their food is one of the best indicators that water quality is not optimum and necessitates further investigation.

To get the most from your fish in aquaponic systems, we do not recommend mixing species or fish of different ages together. Doing so will usually result in health or cannibalism problems and losses will occur.

Health

From time to time, fish will get sick. Health problems usually occur when the fish are stressed from poor water conditions, not ideal water temperature, aggressive behavior, poor diet, or sometimes it can be from their environment. Examples of such that we have seen include- toxins leaching out of grow bed media, using culture tanks that have previously being used for harsh chemicals, using old or 2nd hand plumbing and glues/ silicones. When constructing your system, it is best to always use food grade materials and media/ pumps that are meant for use with fish.

As a general rule however, once you become familiar with your setup and the fish you will be able to observe behavior that is conducive with sick or diseased fish. When this happens, drop us a email, give us a call or talk to someone who has experience with fish diseases. There is plenty of information available on the internet from aquarium based sites which will help you to identify the disease/ problem.

If the fish do get a disease that requires treatment with a chemical medication, it is important to note that all medications used too treat will in some way harm your plants. For this reason, it may be necessary for you too isolate the grow bed, or remove the fish to a separate tank with adequate filtration. 

We are one of only 2 Hatcheries that subscribe to a Health Surveillance Program that is conducted by DPI's Biosecurity Queensland. This program is at the highest level of health surveillance available, and involves regular sampling of fish for pathology to ensure overall good health of all our stock. We also contract Future Fisheries Veterinarian Matt Landos too help with any fish health issues that occur and receive annual audits on our processes. We are also active participants in the Aquaculture Association of Queensland Hatchery Quality Assurance Program that ensures that the fish you receive have been handled correctly according to all regulations, including disease and prophylactic treatment.

We will never knowingly sell sick, diseased or un- healthy fish. If you suspect this to be the case, please contact us as soon as possible.

One issue that we have identified with some customers is regular 'salt bathing' utilizing a cage or pen setup. Whilst the use of salt and salt bathing, when done correctly, is a very effective treatment for many fish ailments, the use of a cage setup and the stresses involved with transferring the fish rapidly from one water body to another can be counter- productive and result in further health issues or losses. We do not recommend the practice of weekly preventative salt bathing using a cage. It may also be necessary to long at other issues if regular salt bathing has become neccesary.

If you have a health issue with your fish, please email or call the office to discuss.

 

Harvesting and Eating

Once your fish reach a plate size, to ensure that the fish taste as good as possible, we recommend 'purging' the fish for about 1 week. This ensures that any off flavors that are associated with farmed fish are reduced, as well as toning up any excess fat in the flesh. The process involves holding the fish in clean, filtered water and withholding food for the period. The addition of 5g/L of flossy salt (available from produce stores) for this period also helps to sweeten the flesh.



 

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