In this article
Aquaponics combines fish, plants and bacteria in a recirculating water loop. It can be a rewarding production and learning project, but it depends on inputs, electricity, monitoring and maintenance. This guide explains how it works, the equipment, choosing fish and plants, and the constraints to check before buying or building a first system. Aquaponics isn't the universal answer to food self-sufficiency, but it's a coherent way to grow vegetables and protein in a small space, year-round, with moderate daily management once the system is stable.
In short
- Fish produce ammonia, bacteria convert it to nitrates, and plants feed on them.
- Starting up the biofilter generally takes four to six weeks, with daily testing.
- In Quebec, the system must be indoors or in a greenhouse, and protected from power outages: without aeration, fish can die quickly.
- To start: a 1:1 fish tank to grow bed ratio, hardy fish and leafy greens.
- Never release fish into the wild, and check the rules of MAPAQ, the provincial wildlife ministry and your municipality.
How an aquaponic system works
The system relies on three partners: fish, plants and nitrifying bacteria. The fish's nitrogen waste feeds the plants after being converted by the bacteria. This balance must be maintained: the system isn't self-sufficient and requires, among other things, fish food, oxygen, water circulation and regular testing.
The word "aquaponics" combines aquaculture (raising fish) and hydroponics (growing without soil). What makes it unique is that these two systems don't run separately: they depend on each other.
The four-step cycle
Fish produce ammonia through their waste. At high concentrations, this ammonia is toxic to them.
The ammonia-rich water is pumped to the plants' grow bed.
Nitrifying bacteria, naturally present in the bed (the biofilter), convert ammonia into nitrites, then nitrates, a form of nitrogen plants can absorb.
The plants take up some of these nutrients, and the water returns to the tank. Their presence alone doesn't guarantee water quality: monitoring, filtration, aeration and maintenance are still needed for the fish's well-being and for the system to work.
What experience shows
The biofilter is the most critical part of the system. Establishing it generally takes four to six weeks at startup, a period during which ammonia and nitrites must be tested every day. Stabilizing the biofilter is often beginners' main challenge.
To work properly, an aquaponic system needs a pump that runs several times a day, constant aeration of the tank and daily fish feeding. These constraints must be planned from the design stage.
Advantages and constraints
Aquaponics has real advantages over traditional gardening or raising fish separately, but also constraints worth assessing honestly before you start.
Advantages
- Recirculated water: consumption depends on losses, top-ups, crops, climate and design; no savings percentage applies everywhere.
- Nutrients: fish waste feeds the plants, but the balance and any deficiencies must be monitored.
- Produce: choosing aquaponics doesn't automatically qualify for organic certification; each input and requirement must be checked.
- Two harvests in one space: vegetables and fish.
- No digging: systems are usually set up at waist height.
- High yield: once stable, the system produces quickly.
Constraints
- Dependence on electricity: pumps and aeration run continuously; a long outage can compromise the system.
- Year-round operation: shutting the system down destroys it, because the biofilter can't survive long stoppages.
- Feeding fish every day: hard to reconcile with frequent absences without an automatic feeder.
- Initial learning curve: starting up the biofilter requires close monitoring.
- Significant startup cost: pumps, lighting, tank and test kits.
Watch out in Quebec
Dependence on electricity matters especially with our winter outages. Without backup power (a generator used outdoors, a UPS, a battery), an aquaponic system is vulnerable during an outage of several hours in the middle of winter: fish can die quickly if aeration or tank heating stops. A battery-powered air pump is a simple backup to have on hand. For backup power, see our guide Off-grid solar power.
Aquaponics or hydroponics?
Hydroponics uses the same soil-free growing principles as aquaponics, with similar pumping and drainage systems. The big difference: there are no fish, so nutrients must be supplied as fertilizer.
| Criterion | Hydroponics | Aquaponics |
|---|---|---|
| Nutrients | Fertilizer to buy (recurring cost) | Supplied by fish waste |
| Water | Periodic draining to prevent salt buildup | Closed loop, less draining |
| Monitoring | Frequent nutrient checks | Less intensive once the biofilter is established |
| Production | Vegetables only | Vegetables and fish |
| Startup | Fast | Several weeks (biofilter) |
Equipment you'll need
An aquaponic system can be built from salvaged materials or new components. Either way, the essential parts are the same. Here are those of a basic system.
The fish tank
Choose a durable, watertight tank suited to fish and to food use. A salvaged container must never have held incompatible products (chemicals, fuel). Plan a base that can support the weight of the water (1 kg per litre, or about 8.3 lb per US gallon), access for maintenance and protection against overflows.
The right volume
Sizing depends on the fish, the biofilter, aeration and how the system is managed. A large volume buffers some fluctuations, but the often-cited 190-litre (50 US gallon) threshold doesn't suit every project. Materials in contact with the water must be compatible and not release substances harmful to fish.
The grow bed
This is where plants grow and where the biofilter's bacteria live. Food-grade plastic containers are generally used. The recommended minimum depth is 30 cm (12 in).
The growing medium
The medium serves four functions: anchoring plants, hosting nitrifying bacteria, regulating temperature and holding air and water. The usual depth is 30 cm (12 in).
The most common medium is expanded clay (Hydroton-type), valued for its porosity and chemical neutrality. Expanded shale is a cheaper option of slightly lower quality.
Some links below are affiliate links: we may receive a commission at no additional cost to you. Products are examples by function, to choose according to your needs; buying the entire selection is unnecessary.
Media to avoid: sand, perlite and vermiculite (they clog the system); soil, peat and wood chips (they decompose and change the pH); anything smaller than 1.3 cm (½ in) or larger than 2 cm (¾ in) in diameter.
Plumbing
Plumbing moves water between the tank and the grow bed. Its sizing is critical: too little, and ammonia builds up in the tank; too much, and the roots drown.
You'll need a pump, non-metal pipes, seals, timers and a distribution system in the grow bed. Avoid any metal in the water circuit: some metals are toxic to fish.
What experience shows
Plumbing is often the sticking point for people without experience in this area. Asking someone who knows plumbing to help with the initial installation, while watching and asking questions, helps you understand the system and avoid costly mistakes at startup.
Aeration
Dissolved oxygen needs vary with the species, temperature and fish density. Design aeration from the benchmarks specific to the fish you choose and check it with measurements. The point at which a fish starts to struggle isn't a normal operating target.
Falling water contributes to gas exchange, but doesn't prove aeration is sufficient. Plan a suitable air pump and diffusers, oxygen monitoring if your project requires it, and a backup in case of an outage.
Lighting
Outdoor systems in warm climates don't need artificial lighting. In Quebec, however, indoor systems and greenhouses need extra light, especially in winter, when sunlight isn't enough to keep plants actively growing.
Needs vary with the plants (fruiting plants are more demanding than leafy greens), the system's area and available natural light. Grow lights also give off heat, a factor to include in temperature management.
Monitoring equipment
Regular water testing is essential, especially at startup. Test pH, ammonia, nitrites, nitrates, temperature and chlorine if you use tap water (let it stand or use a suitable dechlorinator before adding it).
Ready-made kits
Complete kits exist for beginners who want to skip the design stage. Their advantage is that they're already tested, with a pre-set pump and timer. Their main drawbacks: high cost and little flexibility in sizing, and the tank is rarely included.
A starter kit can help you understand how a system works in practice before designing a custom setup.
The AquaSprouts kit, for example, is designed to fit a standard 38-litre (10 US gallon) aquarium. It's a good hands-on introduction without a big financial commitment.
Choosing your fish
Your choice of fish depends on several practical factors: the room temperature, tolerance to pH swings, oxygen needs, diet and intended use (ornamental or food).
Hardiness
Some species are very sensitive to change: a swing in temperature or pH can kill the whole population. For a first system, whose parameters fluctuate more during the break-in period, choose hardy species.
Choose your fish with a knowledgeable supplier, considering their adult size, water parameters, animal welfare and the applicable rules. A fish known to be hardy isn't a "learning consumable": prepare its environment before introducing it and don't plan losses as a normal step.
Oxygen needs
You can't infer oxygen needs from a species' native habitat alone. Check the species' requirements, its size and the planned density, then size aeration to the temperature and the fish biomass actually present.
Water temperature in Quebec
Check all year round
In Quebec, check the room and water temperature throughout the year. Tilapia needs warm water; trout and char need cool water and plenty of oxygen. No choice of species automatically makes an unheated room suitable. Compare the species' temperature range, your heating and cooling capacity, the costs and backup options.
Feeding
Give food suited to the species and its growth stage. Don't replace it with table scraps: unsuitable food degrades water quality and fish health. Adjust the quantity, remove uneaten food and monitor the system's parameters.
Commonly used species
For beginners
- Goldfish: ornamental, very hardy, inexpensive.
- Tilapia: edible, hardy, warm water.
- Carp: edible, tough, omnivorous.
For established systems
- Trout: cool water, edible, popular flavour.
- Bass: cool water, tough.
- Yellow perch: suited to Quebec, edible.
- Arctic char: cold water, local production.
Never release aquarium or farmed fish into a lake or stream: goldfish, for example, are an invasive species in several Quebec waterbodies. Some species are regulated: check before you buy.
Choosing your plants
The pH of an aquaponic system generally settles around 7 (neutral). Plants that need very acidic or very alkaline conditions are therefore poorly suited. The main nutrient source is nitrogen, as nitrates: nitrogen-hungry plants give the best results.
For beginners
- Lettuce and mesclun
- Spinach
- Kale and other cabbages
- Herbs (basil, mint, parsley)
- Other leafy greens
For more mature systems
- Tomatoes (more demanding in nutrients and light)
- Peppers
- Zucchini
- Cucumbers
What about root vegetables?
Potatoes, carrots and beets can technically grow in aquaponics, but the mineral medium deforms them and yields are disappointing. They're generally not recommended in a standard aquaponic system.
Designing your system
Types of systems
Three types of systems are used in home aquaponics:
Media bed
Plants grow in a bed of medium (expanded clay or shale). It's the most versatile and best suited to beginners: a shorter learning curve, compatible with most plants.
Nutrient film technique (NFT)
Plants sit in channels with a thin stream of water running through, without medium. It's only suited to plants with small roots, mainly lettuce.
Deep water culture (rafts)
Plants float on foam boards above the water. Used in large systems, it's less suited to small home systems.
Location
Location determines every other choice: lighting, temperature management, weight to support and access for daily maintenance. A system is hard to move once installed: make this decision carefully.
Outdoors
Only viable in temperate regions without harsh winters. In Quebec, it's only suitable for a short summer period, which goes against the year-round operation the biofilter requires.
Indoors
The logical solution in Quebec. It requires artificial lighting in winter, humidity management to prevent mould and a check of the floor's load capacity for large systems.
Mobile (brought in for winter)
A system designed to move between outdoors in summer and indoors in winter. It must be planned from the design stage (casters, transportable dimensions).
In a greenhouse
A greenhouse can extend the growing season, but requires studying temperatures, energy, humidity and infrastructure. Check zoning rules and permits before building: a greenhouse alone doesn't guarantee year-round operation.
Sizing
Determine the tank volume from the fish's needs and the complete design. Water volume affects stability, but doesn't replace a good biofilter, aeration or careful management. Also assess the load on the ground or floor.
The ratio between the tank volume and the grow bed volume is the most important sizing parameter. Sylvia Bernstein, a recognized aquaponics authority, recommends a 1:1 ratio for beginners: a tank volume equal to the grow bed volume. This ratio ensures reliable operation while you learn.
The balance between the tank, biofiltration and crops depends notably on fish biomass and the amount of food given. A volume ratio alone doesn't justify a larger population: use a documented sizing method suited to your system.
Fish density
Density should be set based on the expected adult biomass, the species, aeration, feeding, filtration and the monitoring you can provide. Two commonly cited shortcuts shouldn't be used as stocking limits:
- Growing area: on its own, it isn't enough to determine how many fish can live in the tank.
- Tank volume: it must be assessed with fish biomass, species and system capacity, without turning a generic ratio into permission to stock.
Fish grow
Start with a density below the system's maximum capacity, then increase gradually as the fish reach adult size: you'll reduce the risk of throwing the biofilter off balance.
Estimating costs
The cost of an aquaponic system varies widely depending on design choices and salvaged materials. A working system can be built cheaply with reused containers, or represent a significant investment with new equipment and a greenhouse. Get current prices before committing.
Startup costs (one time)
- Tank and grow bed
- Growing medium
- Plumbing (pump, pipes, timers)
- Aeration
- Lighting (indoors)
- Water test kits
- Fish, seeds or starter plants
Recurring costs
- Fish food
- Electricity (pump, aeration, lighting, any heating)
- Water top-ups (evaporation)
- Replacing plants and fish
Start with a project whose monitoring and maintenance you can handle. Prepare the environment, test the equipment and plan your response to outages before introducing fish. Fish that are cheap to buy need just as much care and good conditions as any others.
Resources to go further
This guide covers the basics, but detailed design, building the biofilter, correcting pH imbalances and pest control call for more resources. Sylvia Bernstein's book Aquaponic Gardening is one of the most complete references: in nearly 300 pages, it covers both the biological principles and the practical details of building and maintenance. An online course on Udemy accompanies it with visual content: the book to understand the principles, the course for hands-on practice.
Summary
Remember
- Start at a manageable scale, with permitted species suited to the prepared environment.
- Plan a 1:1 tank to grow bed ratio to start.
- Test parameters daily for the first 4 to 6 weeks.
- Choose fish suited to the room temperature.
- Plan backup power for aeration and the pump.
- Start with leafy greens (lettuce, spinach, herbs) before fruiting plants.
Avoid
- Shutting the system down: the biofilter can't survive long stoppages.
- Using metal parts in the water circuit.
- Starting with sensitive species before mastering the parameters.
- Underestimating dependence on electricity during outages.
- Growing root vegetables (disappointing yields).
- Skipping the biofilter startup phase to go faster.
Frequently asked questions
Is aquaponics realistic in an apartment in Quebec?
A small system (a 75 to 150 litre aquarium, or 20 to 40 US gallons, with a suitable grow bed) is doable in an apartment. The main constraints are total weight (water, medium, structure), humidity management to prevent mould and artificial lighting for most of the year. Production remains modest: enough for herbs and lettuce, not for food self-sufficiency. Also check your lease or condo rules.
How long does it take to start up a system?
Starting up the biofilter takes time, generally several weeks, and must be monitored by testing ammonia and nitrites. A fixed date isn't proof the system is ready. Prepare the cycle and confirm good conditions before introducing fish; never use them to test an environment that's still toxic.
How much electricity does an aquaponic system use?
It depends on the system's size and equipment. A pump for a small home system draws 10 to 50 W while running. Lighting is often the biggest load: a full-spectrum grow light for 1 to 2 m² (11 to 22 sq ft) draws 150 to 400 W. Water heating, if needed, comes on top. A backup solar system can reduce vulnerability to outages.
Can aquaponics contribute much to food self-sufficiency?
A medium-sized system (a 500-litre tank, about 130 US gallons, and a 4 to 6 m² grow bed, 43 to 65 sq ft) can cover a good share of a household's leafy greens and herbs, with a worthwhile fish harvest. For a bigger contribution, a greenhouse or large outdoor system remains the most effective setup. Aquaponics is a serious complement to other practices, not a complete standalone system at household scale. See also Winter gardening.
Do I need a permit to set up an aquaponic system in Quebec?
Check your project with MAPAQ, the provincial wildlife ministry and your municipality before buying fish or building. Rules may cover activities, species, their transport, water, discharges and facilities. Personal use doesn't guarantee an exemption. Present your setup to find out which permits apply.