How to Raise Salmon in Your Aquaponics System
Aquaponics is an eco-farming technique that combines hydroponics with aquaculture to allow both plants and fish to grow in a single decoupled, manmade ecosystem. Aquaponics systems can be setup utilizing one of three methods; media based systems, nutrient film technique NFT, and deep water culture DWC. Each system can be configured to meet varying requirements, and this flexibility allows the technique to be applied for indoor, outdoor, domestic and/or commercial use.
Why Choose Salmon for Your Aquaponics
Salmon is reported to be the most popular fish in the world, it makes it onto the dinner plates of over 22 million daily, and it also one of the most healthy species of fish thanks to the high levels of omega-3 fatty acids and lower levels of mercury. Furthermore, some experts actually believe farmed salmon to be healthier than wild salmon since their environment can be closely monitored and kept in optimal condition, whereas salmon in the wild are exposed to higher risks and lack the helping hand of a human should any problems develop.
Boasting an unbeatable taste, high market value and being jam packed with nutrition, there are a several good reasons to choose salmon for your aquaponics setup. However, it is important to note that salmon are not the easiest species of fish to raise; the size, number of days to maturity and their sensitivity to disease can all throw up hurdles for both beginners and experts like, but with the right guidance it’s possible to succeed in growing aquaponics salmon the very time round, and have an enjoyable time doing so.
Species of Aquaponics Salmon
There are 8 species of salmon worldwide, 7 of them are native to the Pacific, with 5 occurring in North American waters and 2 in Asia. Then there’s also just one species of Salmon that comes from the Atlantic.
All species are edible; if you see warning signs noting the risks of consuming chum, masu, pink and sockeye, this is typically due to them regularly being transported unfrozen. In some cases you will know if the fish are fresh, or have been transported safely, but it’s much more likely you’ll be unaware exactly how the fish arrived at its final destination, in which case, proceed with caution.
Species of salmon suitable for aquaponics include:
Atlantic, which also have many aliases:
- Bay salmon
- Black salmon
- Caplin-scull salmon
- Sebago salmon
- Silver salmon
- Outside salmon
The most common species of salmon to raise in aquaponics are Atlantic, Coho and Chinook. Atlantic salmon is the most popular and is grown worldwide; it’s the species most like trout, a species in the same family that’s actually a little bit easier to farm. Coho is commonly farmed in the U.S. and Canada, whereas Chinook is regularly farmed in New Zealand and Australia, where it’s commonly known as King Salmon.
Advantages of Selecting Salmon for Aquaponics
Salmon are known to be one of the more challenging fish to grow in aquaponics, that said, there are a variety of benefits that, depending on your situation, could outweigh any of the potential disadvantages.
Advantages of raised salmon in aquaponics includes:
Taste: For many, the best advantage of raising salmon in aquaponics is the taste. There’s a reason it’s cited as the most popular fish in the world, and considering its high market value, it certainly isn’t the ‘cheap’ price earning this claim, it is of course the taste.
Health: In addition to tasting great, salmon is rich in protein and chock-full of essential nutrients such as omega-3 fatty acids, selenium enzymes, B vitamins and vitamin D.
Cost savings: As previously noted, salmon isn’t only the most popular fish to eat globally, it also has a high market value, which means you stand to save a notable amount growing your own over purchasing fresh off the shelf.
Easy Companion Fish: Salmon are social fish and do well with other species of a similar size. Trout are popular companion fish for salmon since they are both in the same family and typically grow to a similar size.
Cold Temperature Tolerance: Salmon enjoy cold waters and therefore thrive in aquaponics systems setup in cooler climates. They are extremely tolerant to changes in temperature as long as the overall range is still under 20°C / 68°F, but above freezing.
Disadvantages of Rearing Salmon in Aquaponics
Unfortunately there are several downsides to choosing salmon for your aquaponics. Mind you, none of these issues are impossible to overcome; each just requires a little special care and attention.
Food expenses: Salmon are picky eaters and typically only eat meat due to their predatory nature. Whilst this won’t be any more ‘difficult’ per se, it may require more time and expense. In some cases it can be possible to feed them on specially formulated pellets/fish food but this too will not be cheap and there’s always the possibility your salmon may not take well to the diet.
Time: Salmon take around 2 years to reach maturity. This is much longer than other species of fish suitable for aquaponics. For example tilapia can be harvested within a couple of months, and even trout, a similar species to salmon only take 1 year to reach maturity.
Size: this isn’t always a downside since the substantial size of the fish provides lots of harvestable meat with far fewer fish, which then makes monitoring easier. However, large fish means a large volume of water, so you’ll need enough space to accommodate the volume of water needed to satisfy stocking density requirements.
Cool temperatures: another point that can actually be benefit, since salmon enjoy cool waters they’re a great choice to raise in colder climates, but this very same benefit immediately becomes a problem in warmer climates, where it simply may not be possible to raise salmon, without unjustifiably huge cooling expenses.
Fish Care For Aquaponics Salmon
When it comes to operating a successful aquaponics system with salmon, you’ll need to pay special attention to the health of the fish, more so than other species of fish. This is mainly due to the fact they have a tendency to develop disease easier than other fish; the size can also pose a problem as their larger stature requires lots of space to thrive. Nevertheless, raising aquaponics salmon can be extremely satisfying, and as long as you provide the necessary care for the fish, the plants will also thank you and the whole ecosystem will flourish.
Diet Feeding And Nutrition
Salmon are big eaters and go through a lot of food. You should aim to feed them between 1-2% of their body weight per day; they typically grown on average 0.875lbs per month, so you can increase the amount incrementally to match.
Initially hatchlings do not need feeding since they feed off their yolks for up to 40 days. Following which they’ll need feeding between 8-12 times a day. This can slowly be reduced to 3-4 times as they become adults.
In general they require a similar diet to what they would get in the wild. This includes insects and plankton when they’re young, then as they grow into adults they’ll eat almost any fish smaller than them; including eels, shrimp, and even squid. It is possible to feed some salmon on commercial fish pellets, however not all take to this diet well, so you may have to revert back to live feed, or a mix of both.
The feeding requirements for salmon are quite substantial, they eat a lot and frequently. For this reason many growers install automatic feeders to take care of the task. Of course there isn’t an easy DIY solution for automated feeders, so initial setup costs will increase should you wish to install on of these off-shelf auto-feeding units.
Disease Prevention and Treatment
Salmon are a species prone to disease. That said, it’s not too difficult to keep them free from developing common health issues. The diseases salmon are most likely to develop include red mouth and fin rot. The latter of which produces symptoms fitting of the name, whilst the prior causes hemorrhaging of the mouth, eyes and fins.
To avoid these and other diseases you’ll need to maintain impeccable water quality, as well as a well balanced stocking density. Remember to calculate the water volume based on the final size/weight of fully-grown adults, not the size/weight they are when transferred to the tank.
How To Prevent Disease in Salmon Aquaponics
It goes without saying that prevention is better than a cure, and aquaponics is no different. In order to stop diseases and/or other health issues developing you can follow best practices such as:
- Use clean water from trusted source
- Use chlorine-free water
- Keep water clean
- Aerated water sufficiently
- Use reputable suppliers/pet stores
- Quarantine new fish
- Acclimate new fish
- Use good high quality food
- Don’t overfeed
- Remove uneaten food
- Monitor pH, ammonia, nitrites, nitrates, DO, and temperature on a regular basis
- Set up system in a shaded area
- Practice strict hygiene procedures similar to handling food
- Keep your equipment and environment clean
- Treat any disease immediately
How To Treat Common Diseases in Aquaponics Salmon
When salmon develop disease the most common treatments include medications such as Levamisole and praziquantel for deworming, and antibiotics like metronidazole, nitrofurazone or erythromycin for bacterial infections.
These treatments are highly effective, but like all medications do come with side effects and adverse reactions, as well as the risk of developing a resistance to the drug.
Water Quality Management: Parameters
Maintaining clean water is one of the most important factors in the operation of any aquaponics setup. Not only is water the lifeline for fish, plants and the beneficial bacteria all living within the ecosystem, it’s also your primary warning indicator that can alert you when something is wrong.
All important levels are measured from the water; including temperature, pH, dissolved oxygen DO, nutrient levels (nirates and nitrites) and toxins (ammonia). Therefore regular maintenance to ensure the cleanliness of the water is crucial in keeping the system balanced.
Water Volume Vs Stocking Density
On average salmon grow between 71-76cm / 28-30 inches and weigh up to 3.6-5.5kg / 8-12lbs but can easily grow up to 147cm / 58 inches in length and 75kg / 126lbs.
The suggested stocking density for each 20kg / 44lbs of fish you’ll need 1000 liters / 264 gallons of water.
The optimal range for salmon to prosper is between 15°C / 59°F to 19°C / 66.2°F. At the extremes they can survive in waters as low as 0.5°C / 32°F and as high as 20°C / 68°F, but temperatures outside this range are immediately lethal.
Note: The cooler waters necessitated by the salmon can cause issues with the plants. Extreme cold can affect the system’s ability to support certain species, namely those that cannot survive cold weather climates. Fortunately many of the species commonly chosen for aquaponics can thrive in the cooler temperatures typically associated with aquaponics setups, so whilst your options might not be as plentiful as soil gown setups, you should have no trouble finding plants you want to grow, and eat.
Alternatively, the decoupled configuration of the system can be leveraged to further advantage here; by separating the grow bed far from the fish reservoir you’ll be able to add heating to raise the temperature surrounding the plants. This is a rather complex upgrade however it does solve any plant growing issues caused by the cold climate requirements of the salmon. The modification can also be streamlined by utilizing grow lights to produce the additional heat some plants may require.
Dissolved Oxygen (DO)
Salmon require concentrations of dissolved oxygen on the higher end of the scale when compared with most other species of fish. The average safe range of DO for most freshwater fish is between 1-6 mg/l, and salmon thrive with levels of 6 mg/l and above.
Being in the same family as trout this makes sense. These energetic species can travel astonishing distances in the wild, and together with their large stature, the evolutionary brothers have some of the highest DO concentration tolerances of any freshwater species.
The ideal pH range for salmon is between 6.5-8.5. Like trout, this is higher than most other fish, which typically require pH levels no higher than 7.5.
If you need to raise the pH levels you can:
- add potassium hydroxide, calcium hydroxide, calcium carbonate or potassium carbonate
On the other hand should you need to lower pH levels, you can:
- allow the nitrification process to naturally reduce levels
- use a pH lowering agent such as nitric, muriatic, or phosphoric acid
Nitrification: the most important process in the system, salmon provide waste rich in ammonia which the beneficial bacteria can convert into nitrites for the plants to feed on.
It’s advised to keep ammonia levels below 3ppm, and nitrites below 0.8ppm. You can test these parameters using a six-in-one test strip.
Should you need to increase nitrites you can:
- add more fish
- add more beneficial bacteria
Otherwise if you need lower levels you can:
- add more plants
- remove some fish
You can also adjust these levels by changing the water; switch out just 15-20% to be safe.
Like most aquaponics fish, salmon do not require direct sunlight, but they do require some indirectly. Setup you system in a shaded area, alternatively you can construct some form of shading to protect your aquaponics fish tank from direct sunlight.
Best Plants to Grow With Salmon Aquaponics
As noted salmon require cooler temperatures, and this will limit your options of plant species you’ll be able to grow. In this case it’s best to grow plants that can easily handle in cold weather, fortunately many of species already popular with aquaponics growers can survive the cold; plants such as:
- Lettuce (winter varieties)
- Spinach (Giant Winter, Tyee)
- Swiss chard
- Butternut Squash
As mentioned salmon are one of the more difficult species to rear in aquaponics; in addition to the size the cool temperature requirements can pose problems for some plant species but with that in mind, salmon are an extremely satisfying fish to raise in aquaponics. Harvesting at the end of such a long maturity period, and then enjoying the most delicious tasting fish meat possible, all whilst knowing you paid a fraction of the price, benefited from the support it provided for the plants in you system, and learned a thing or two a long the way, are all factors that should sway you into trying salmon in your next aquaponics setup.
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