Aquaponics: How to Use Fish to Grow Delicious Food

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It’s frustrating when you can’t do something you want to.

You can feel that way about gardening as well.

You need to have a good space to grow vegetables. And you need the soil to be suitable as well.

But what if you don’t have much space. Or good, fertile soil. Is there a way out of this?

The good news is that there is. And it’s known as aquaponics.

What is aquaponics?

Aquaponics is a combination of fish farming and hydroponics. The method makes use of two essential elements – an aquaculture sub-system and a hydroponic sub-system.

The method can be used year-round as it is an indoor process, making it a great option for farmers in all environments.

While the two areas are kept separately, they work together by a cycle of water which flows between them. The fish who live in the water are fed and produce waste.

The waste is then transferred through the water to the plants, who use the waste as a natural fertilizer to help them grow.

As they grow, the plants give off nitrogen, allowing purified water to return to the tank for the fish life.

This technique allows the raising of fresh fish and vegetables at the same time.

What are the benefits of using aquaponics?

Requires less space

Growing in soil takes up space no matter how small garden you intend to create. This means less room is available for other outdoor activities.

You either need to have enough space or grow a vertical garden that helps with efficient gardening.

With aquaponics, there’s no dependency on the soil. This means you can set up your garden in any location you prefer.

Easy to set up

The soil in your garden could contain large quantities of clay or sand. It may have poor drainage. Or might contain chemicals harmful for growing plants.

All these conditions could make your garden soil unsuitable for growing vegetables.

You either need to amend the soil for a few months or years to get it in good shape. Or you need to consider options like raised bed gardening or container gardening.

Amending the soil can be quite resource-intensive taking up some of your time and money.

Aquaponics does not need soil which means you don’t need to worry about soil conditions. You can set up the system and won’t need to worry about amendments.

Requires less maintenance

Gardening in the soil can literally be a pain in the neck sometimes. You need to take care of the pests, diseases, and weeds in the garden.

You need to water the garden and resolve any issues with the soil. This means you spend some time bending, lifting, harvesting, moving things around the garden. Which might be a hectic task for older folk.

With aquaponics, you don’t need to worry about heavy maintenance. You can place the system at a height, so it’s easy to reach. That makes it easier to maintain and harvest the plants.

Helps with efficient use of water

Gardening in the soil means you need to water it often. This leads to problems like overwatering or underwatering. Both cause serious damage to the plants.

A lot of the water used drains out along with the nutrients in the soil. Some of it also evaporates from the surface of the soil.

An aquaponic system uses recirculation of the nutrient-rich water. This means it needs less than 1/10th water you would need with soil based gardening.

Beneficial for the environment

We know that aquaponics will save a ton of water that is lost with soil based gardening.

You also don’t need to use harmful chemicals with pesticides and fertilizers. The fish waste acts as a natural fertilizer in the system.

You get to grow food with vegetables and fish in a sustainable manner.

Helps create an abundant food supply

Gardening in soil limits how much food you can grow. That depends on the space you can manage.

Aquaponics can provide you with a very efficient food production system. You can get the benefit of growing plants as well as fish.

You can scale the system as much as you want based on your needs. This can be used to produce food in a sustainable manner.

And food that is abundant and provides nutrition to a large number of people in your location.

What are the disadvantages of aquaponics?

Can be expensive

While the system is considered to be less expensive over time than traditional soil planting, you may still see a rise in cost at some point in time.

For example, your heating costs in the winter may see a rise for those who live in cooler climates.

With water pumps, lighting and heating all demanding a lot of power to be used, it is suggested that you look to a more sustainable source of power, such as wind or solar, to keep your costs to a minimum.

Can take up space

Despite taking up less space than traditional methods of gardening, the system does require additional space for the fish tank that other methods.

Needs maintenance

In order to maintain the water quality, you will have to continuously test and monitor the water.

You also need to perform a routine check to ensure all the mechanical parts are working correctly.

The maintenance also involves checking the health of your fish. You need to take care of any diseases or overpopulation that may mess up the system.

How does aquaponics work?

An aquaponic system mimics the natural waterways found on Earth, providing food in a sustainable way.

After you feed your fish, they will excrete waste in the form of ammonia through their gills as well as in the form of urine.

The heterotrophic bacteria eat up the fish waste, plant waste, and uneaten fish food. There release ammonia in the process.

The ammonia is then converted to nitrite and then nitrate by nitrifying bacteria that are naturally found in the water.

These bacteria are found attached to tank walls, the underside of rafts, organic matter, and any growing medium used, as well as in the water column.

The nitrate produced by the bacteria is then consumed by the plants, which helps them grow. This process also helps to keep the water clean for the fish to live.

What can you grow with aquaponics?

You can grow a variety of fish and plant life in this type of system. The fish you keep should be freshwater, with the same pH and temperature needs as the plant life.

The most popular fish used for this purpose is tilapia and barramundi as these types of fish are not only able to grow quickly, but they are also extremely tolerant of a variety of water conditions.

Good vegetable choices for this type of garden include those that do not require a lot of nutrient input. Small vegetables such as kale, lettuce, arugula, watercress, herbs, leeks, radishes, and spinach do particularly well.

For those looking to grow things such as cucumbers, tomatoes, beans, broccoli or cauliflower, a more advanced system may be necessary as these require additional nutrients.

Plants that require acidic or alkaline water are not considered to be great choices for this type of system, as the pH level they require could cause harm to your fish.

Some plants you can consider growing with aquaponics include lettuce, kale, collards, peppers, herbs, tomatoes, cucumbers, beets, radishes, carrots, beans, peas, cabbage, broccoli, cauliflower, bananas, oranges, lime, pomegranate.

What are the different types of aquaponic systems?

Deep Water Culture

More commonly used in commercial settings, the deep water culture system has your plants floating on the top of the water, allowing the roots to hang down.

This can be easily accomplished by placing a piece of foam on top of your fish tank for the plants to grow through.

The more popular way of creating the system features a water pump connecting a fish tank to a separate water system where the plants are floating on a raft through a filtration system, allowing the plants to extract the nutrients they need.

This system is suitable for growing leafy greens that have low nutrient requirements.

Media-Based

The simplest system available today, this method features containers that are filled with rock, expandable clay, or something similar.

A water pump is used to bring nutrients over from a separate fish tank, allowing plants to flourish through the rock or clay media.

The water can either be brought over in a continuous manner or through a system of flooding and draining.

The medium like clay pellets helps with biological and mechanical filtration. This system is suitable for growing salad greens fruiting plants, and herbs.

Nutrient Film Technique

Nutrient film technique is more commonly used in hydroponic farming, but it is becoming quite a popular method in aquaponics.

The system allows for a thin film of water to be pumped through a series of small, closed gutters. The water flows through a trough-like PVC pipe.

The plants are placed in holes with roots dangling in the water.

This system is a great way to grow leafy green vegetables. One problem would be if the plants are large and take up a lot of space in the gutter. This will make them too heavy for the drainage system to work correctly.

This system is suitable for small plants like strawberries and herbs. It’s a small system that can also be hung up from the ceiling.

Vertical Aquaponics

The vertical aquaponic system allows the plants to grow in an upward manner, making it a great option for those with a limited amount of floor space who would still like to grow a large number of plants.

The vertical system features plants growing on top of a fish tank. However, in order to achieve a true vertical growing area, there need to be multiple layers.

The trick to this is ensuring that each layer has enough space for your plants to properly grow while receiving enough light.

The water flows from the top to bottom in the system. Each layer is connected by wicking material that absorbs the nutrient-rich water.

The water reaches a trough or fish tank at the bottom.

This system works best for lighter plants. You can grow strawberries, leafy greens, and plants which do not require support.

Locating your aquaponic system

Your system should be placed in an area that receives good sunlight for at least four to six hours each day.

However, you want to be careful as too much sunlight on your fish tank will lead to the growth of algae, which is not healthy for the fish or your plants. In truth, your fish do not need any sunlight.

If you cannot avoid this, you might want to consider a system that has your plants directly on top of the fish tank. This will block the light from reaching the fish.

Keep the time of year in mind as well. A system that receives enough sunlight in the summer may receive a different amount in the winter.

You will also need easy access to power. Because these systems make use of water pumps and possibly air pumps as well, they need a power source to properly run.

You’ll need to be able to access the entire system with ease. So you do not want to place the grow bed in a tight corner where you cannot fit.

For those creating a vertical system, a space of 70cm is typically suggested between layers.

You’ll need to easily access the fish tank, in order to care for your aquatic life.

It’s also important to keep the surrounding vegetation in mind, as contamination from other plant life could kill your fish.

If you have pets or children you want a system that is both pet and child-friendly.

What are the components of an aquaponic system?

Biofilter

Biofilters are tanks that are connected to air pumps. The big surface area of such filters is a thriving ground for the nitrifying bacteria.

The medium that is used in biofilters could be sand, shells, or gravel.

The air pump gets the water from the tank to the biofilter. The biofilter uses the process of nitrification to remove unwanted chemicals but retain nutrients. The nutrient-rich water is then sent to the plants.

There are different types of biofilters available including rotating biological contactors, expandable media filters, fluidized bed filters, and trickle filters.

Plant Bed

The plant bed is the component that is filled with growing media. This helps hold the nutrients from the water that flows through it.

It’s good to have a plant bed made with wood and have a waterproof plastic liner in it. It should be sturdy and lightweight.

You want a plant bed that allows the plant roots to be submerged in the water. A dark color is good as it prevents light from reaching the roots.

Too much light can cause algae growth in the water and you don’t want that.

The walls of the plant bed can be insulated especially if kept outdoors. This helps retain heat in winter and keep it cool during summer.

The size of the plant bed depends on the number of plants you want to grow and the space available. You can consider using vertical plant beds to save some space.

Growing Media

You can choose growing media like hydroponic expanded clay or local crushed rock. You can also use a material like riverstone or shale as the growing media. Rock media can be cheaper compared to others.

You should be careful to check the pH level of such media as it can harm the fish and plant life in the system. The expanded clay is lightweight and pH neutral but the rock material is not.

The particle size matters when choosing growing media for the aquaponic system. This should be between 8mm and 16mm.

If the particle size is too small, the air space will be restricted. If the particle size is too large, the surface area is limited.

Whatever growing medium you choose, it should be easy to plant in, should be clean, and sterile.

Fish Tank

The fish tank is the home for your fish. This is the place where the fish waste will get collected. The bacteria will work on the waste and convert it into nutrients for your plants.

You should choose the fish tank based on your needs. It depends on the space you have, the number of fish and plants you want to grow. The bigger the tank, the more fish you can have, and the more plants you can grow.

The fish tank could be an indoor aquarium tank or it could be a pond outside your house.

You can get ready fish tanks and pond systems to use. Or you can build a custom one for yourself if you have the time and money.

Pump

Depending on the type of aquaponic system you use, you’ll need to install a pump and piping.

If you are using a vertical system, a pump is essential to allow the nutrient-rich water to flow from the tank to the plant bed.

The size of the pump depends on the capacity of your aquaponic system. If you have a small indoor aquarium, a submersible pump may be all you need.

Such a pump helps to move the water from the tank to the plants. And it also helps aerate the water, so a good amount of oxygen is available to the fish, plant roots, and bacteria.

If you have a large aquaponic system, you’ll need an inline pump that generates sufficient power to move the water from the tank to the plants. You’ll also need an air pump that helps aerate the water so enough oxygen is available for the fish, plant roots, and bacteria.

What operations are required in aquaponics?

Feeding Your Fish

Your fish will require dry food that is specialized for the particular type of fish you select to keep.

It is important to purchase the correct food as different types will have different amounts of proteins, carbohydrates, fats, oils, vitamins, and minerals.

You want to feed your fish enough to keep them happy and healthy. Home-use systems will want to feed their fish once per day, while a commercial system will need to feed up to three times each day.

You can feed the fish manually. This helps keep an eye on the health of your fish. Or you could feed them mechanically or on-demand when the fish need food.

Seeding and harvesting the plants

In order to maintain a constant supply, you will need to replenish your plant supply after every harvest.

Leafy plants will mature fast, and indeterminate plants such as tomatoes will bear a lot of fruit during the growing season.

You can choose to directly germinate seeds in the aquaponic system. Or in a separate area using trays that contain vermiculite, perlite, and potting mix.

Once germination has occurred the seedlings can be safely transferred to the system.

Monitoring the system

Both the fish and plant system need to be monitored and checked on a daily basis to ensure the pH level and temperature of the water is constant.

This can be easily accomplished with a water testing kit, which will measure the ammonia, nitrite, nitrate, oxygen levels, pH, and water hardness.

You’ll need to check the health of your fish. Make sure they are eating well and staying active. Look for any fungus, sores, discoloration, or torn fins.

Plants should be checked daily for any diseased areas or pests. Dead plant matter also needs to be removed each day in order for your plants to grow.

Each piece of the system, including the water supply, the aeration system, and the drains, will need to be checked to make sure they are working properly.

Remove any dead or diseased fish and plants. And clean the filters often to keep them in good working condition.

Harvesting the fish

When they are mature, the fish can be harvested. It is a good idea to do this before harvesting your plants.

The fish must be taken out of the tank and placed in a separate system that is free of food. This helps improve the quality of the fish for consumption.

How to choose your fish for aquaponics

Look for fish that do well in crowded environments. They should be able to thrive with fluctuations in pH levels, temperature, and oxygen levels.

The fish should be resilient to diseases and parasites. And should be able to grow quickly.

You should consider fish that have the same pH and water temperature requirements as the plants you are looking to grow. To grow leafy green vegetables, you can choose freshwater fish.

Some fish that do well in aquaponic systems are tilapia, bluegill, sunfish, koi, goldfish, and ornamental fish, such as angelfish, guppies.

The fish you select should depend on whether you want to eat them or simply use as a decoration in the house.

How to choose your plants for aquaponics

The same rules you followed to select fish also apply to select plants. Your plants should do well in crowded conditions.

They should be able to survive with some variation in pH levels, water temperature, and oxygen levels.

It’s best to choose strong plant varieties that can resist pests and diseases and grow well.

You can use a combination of seeds and seedlings to grow your plants.

You should aim to grow plants that you want to eat. Also, it’s good to always have something growing in your aquaponics system.

You don’t want to harvest all the plants at once. This will cause a problem that there are none to absorb the nutrients flowing in the system. You can grow a variety of plants that mature at different times.

Some plants that you can grow with an aquaponic system include:

Lettuce, kale, chard, basil, mint, watercress and chives.

Tomatoes, peppers, cucumbers, beans, squash, broccoli, cabbage, and cauliflower.

Bananas, lemons, oranges, sweet corn, beans, radishes, carrots, and onions.

How can you get started?

Aquaponics can help you grow the vegetables that you want even if you don’t have the space and soil for gardening.

Take the first step to find out the vegetables and fish you want to grow in your aquaponic system.

And you’ll be on your way to creating a wonderful garden in your house.

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