How To Determine The Ideal Fish to Plant Ratio for Aquaponics?

aquaponics fish to plant ratio

Aquaponics is an ingenious, sustainable bio-integrated system of plants, water, and fish. Herein, the plants use the waste materials of fish as the sources of food and nutrients to grow. This indicates that the fish species in the system are fed well.

Aquaponics is a farm setup using a myriad of plants and aquatic species. Different plant and fish species are used according to a number of factors. No matter which combination you choose, it is essential to ensure a sustainable aquaponics setup. For this, you need to strike a balance between the amount of nutrients plants require and the amount of fish waste to be generated.

To get this balance, an appropriate fish to plant ratio is indispensable. In this post, let’s find out how to determine the right ratio for your aquaponics system.

The Need of an Optimal Number of Plants per Fish

In aquaponics, the number of plants to be grown is directly proportional to the amount of fish feed you put in the system. Thus, sufficient fish should be present in the system, and you need to feed them well. A high plant density means a good number of fish and favorable water quality without exchanging large quantities of water or using any complex filter gadgets.

Similarly, the removal of ammonia and nitrites from the fish waste is essential, as it is toxic. A high nitrate level can result in tank water poisoning, which can kill the surviving fish species. To avoid this, more plants are required, as they act as biofilters to clean the water as well as process the wastes.

However, fewer plants may be unable to eradicate these contaminants efficiently. In that case, you may opt to decrease the fish feed to reduce the toxic waste, which means slower fish growth.

That said; you will always consider maximizing your return on investment on plants and fish species in the shortest time, while minimizing the probable risks. For this purpose, it is essential to sustain an optimum balance between nutrient consumption and its production.

Factors Helping in Identifying the Best Ratio

Your aquaponics system is made up of many components or factors, such as plants, fish species, size, and design. Each of them affects the growth of plant and fish species. Thus, a couple of factors affect your fish to plant ratio.

No universally-applicable fish to plant ratio exists, as each aquaponics system is unique. Still, a good ratio will contribute to the balance for your aquaponics setup. Below are the factors to consider for determining the best ratio:

Types of Plants to Be Grown

The amount or concentration of nutrients (fish waste) required significantly relies on their type. For example, herbs, green veggies, peas, cabbage, garlic, and cauliflower need low to medium amounts of nutrients. On the other hand, plants yielding fruits and flowers such as tomatoes need maximum nutritional content. It is suggested to select plants and fish sharing a similar pH level and temperature requirements to grow.

Suggested article: 11 Best Plants For Aquaponics: Best Options & Less Common Plants

Types of Fish Species

There are a couple of fish species that you can nurture in an aquaponics setup. However, you should choose those species that will thrive in your system. For this, you need to consider the following factors:

Water Temperature

Fish that you choose should survive in your climate as well as amidst the water temperature to ensure easy maintenance and electricity efficiency. If the climate is usually cold, consider rearing trout species. If warm, tilapia species are ideal.


Some species are sensitive, while the rest are hardy, due to which they need more care. It is suggested to select a hardy fish that is resistant to diseases and easy to maintain. Some examples of hardy fish species are Koi and Tilapia.

Breeding Tendency

A few species can reproduce swiftly and quietly, such as tilapia. It is essential to observe their stocking density and maintain a separate tank for breeding to ensure the good health of the little ones.

Stocking Density

This term refers to the number of fish you intend to raise in your system. Ideally, you should keep this number small and increase it gradually in the system once you get accustomed to controlling the water quality by modifying the frequency of feeding. Starting with a higher number would mean more filtration. An overstock due to quick breeding may also kill the fish due to less oxygen or sustained nitrate level. The stocking density depends on the total fish length instead of the number. The suggested density is 10 to 20 kilograms per 1000 liter of water. You should also manage stocking as per the feeding needs. A couple of goldfish species requires less feeding, but it will also mean less plant growth.

Feeding Rate

This is an important factor for determining the fish to plant ratio in an effectively maintained aquaponics farm. Around 20% of consumed fish feed is excreted as waste. The quantity of feed you add daily to your aquaponics farm is deemed for per square meter of growing region of plants. This also depends on the feed used and types of plants. For example, for leafy greens, around 40 to 50 grams of fish food is needed per square meter, while 50 to 80 grams is required for fruiting vegetables. This feed ratio ensures sufficient fertilizers for the plants in your system. It is likely to vary as per the plant type, grow beds, and fish species. Grow beds are one of the growth techniques used in the world of aquaponics. Similarly, there are two more techniques, namely, Deep Water Culture (DWC) and Nutrient Film Technique (NFT). Your feed ratio will vary as per the growing technique. For example, in case of a DWC, around 60 to 100 grams of feed daily per square meter is required, while grow beds would need 15 to 40 grams. NFT needs around 15 to 25 grams of feed.


It is essential to cycle a new aquaponics setup prior to planting plants in it. It is a process of launching beneficial bacteria into it so that they can convert the ammonia waste into nitrate nutrients. Thus, bacteria bridge the journey of waste to nutrients.

Aquaponics Design

The type of your system also plays a vital role in figuring out this ratio. This is because it conveys the system’s ability to convert waste into nutrients. The more area in the grow bed, the greater number of fish you can raise.


So, what is the ideal fish to plant ratio? Well, the exact answer depends on a variety of factors discussed above. There is no single ratio that applies to all aquaponics systems. Generally, the volume of your fish tank should be equal to the grow bed volume. This means that the ratio of fish tank to suitable grow bed is 1:1. This can help you to come up with the ratio easily.

It is a fact that starting a novel aquaponics system is like conducting a new experiment. So, it is a bit tricky to sustain fish to plant ratio in a novel system and even for beginners. Thus, it is ideal to get started with fewer fish and then raise their population when you notice that your plants have started to grow. This will ensure sufficient nutrients for the plants. Based on trial and error, you can achieve the best fish to plant ratio for your system.

Suggested articles:
Aquaponics for Beginners – Everything You Need to Know Upfront
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What is Aquaponics Farm? – Types, Benefits and Drawbacks
Aquaponics Fish Food Explained – What Options Do You Have?
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Aquaponics Grow Bed Depth – What You Need to Know
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