Will Fish Eat Plant Roots In An Aquaponics System?

An aquaponics system heavily depends on fish waste in order to provide the plants with the proper nutrients required. One of the most asked questions, when a beginner starts to plan his aquaponics setup, is, will the fish eat the plant roots in the system?

So, will fish eat plant roots in an aquaponics system? Yes, fish tend to heavily eat the plant roots dangling in the water of the aquaponic system that they live in. But you can avoid this by trying different solutions that have worked for other growers as well.

This is a common problem that most of you will face when planning out your aquaponic system, especially if you are intending to place the fish and the plants together in the same water reservoir.

In this article, I will explain how can you get around this problem with some tips and tricks that I hope can help you.

Why Do Fish Eat Plant Roots?

If you are a beginner in this niche, you are probably wondering, how does aquaponics even work if the main source of its nutrients, the fish, is also the reason for destroying it. In order for me to answer this question, we must get back to the history of aquaponics.

Aquaponics has been around for centuries, way long before we did even knew about its benefits. It could be traced back to around 5 years AD. In China, for example, fish and plants were smoothly coexisting together in the rice fields that were flooded by water.

You need to understand that, by nature, plants tend to represent a good source of food for fish. So, how did the rice fields in china continue to grow normally without being distroyed by the fish swimming around?

The answer to this question lies in three different parts:

  • Other food food sources
  • Natural barriers
  • Too many plants to fish ratio

In a big ecological system like rice fields, there is a wide variety of food sources available for fish to feed on. Let it be, worms, insects, or freshwater weeds. Fish can feed on whatever they found. Being constantly in a fed state makes eating and digging for plant roots their last option.

Natural barriers tend to play an important role as well. There are many, hard to reach spots, that fish can’t simply get their hands onto due to the low water level or even the water passages being blocked by old plant stems. However, we will learn how to implement the concept of natural barriers into our aquaponics system in just a few minutes, so, make sure to stay till the end.

The last reason why rice fields are not affected by fish-eating their roots is that simply there is a high plant to fish ratio. By having a large number of a plant to fish ratio, the last thing you can worry about is fish-eating few plant roots.

Now that we have discussed why do fish eat plant roots, it’s time to go further into how are we going to stop it from happening.

How To Stop Fish From Eating Plant Roots In Aquaponics?

Of course, the single, most effective advice I can give is to never put fish and plants into the same aquaponic unit. However, most of the growers who run into this issue are forced to do so because of many reasons such as the lack of space.

1-Fish Selection

If you have no option other than placing the fish into the same aquaponic unit as the plants, choosing the right fish species could save you a lot of trouble.

As a general rule of thumb, as the size of the fish species increase, the probability of them eating your plant roots increases. So, small to medium-sized fish species are considered okay if you want to minimize your loss. By me saying minimizing the loss, I mean that you cannot guarantee that a fish will not mess around with your plant roots. However, certain fish species have a higher tendency to eat plant roots than others.

First, let us mention what are fish species to avoid if you do want to keep your plant roots safe.

  • Tilapia
  • Koi Fish
  • Gold Fish
  • Catfish

You can consider these fish species as the number one enemy to any aquaponic system that has plants placed in the same tank as fish. Tilapia, for example, is considered one of the most common fish species grown alongside aquaponics systems. However, a tilapia can literally devour the roots of an entire floating rack in a matter of days.

Koi fish, Goldfish, and Catfish are also well known for their high bio-waste production that is used efficiently in aquaponics. But also, we cannot turn a blind eye to their excessive eating habits that can threaten the survival of any plant grown with them in the same tank.

On the other hand, there are other fish species that are considered safe around plant roots. But I have to be honest with you, they will not provide your plants with the same nutrition as other large fish species like Koi and Tilapia.

The fish species that are considered safe around plant roots are:

  • Cichlids
  • Swordtails
  • Tetras
  • Rainbowfish
  • Killifish
  • Rams

2-Separate With A Barrier

Do you remember the natural barriers that tended to prevent fish from reaching certain spots in large ecosystems like the rice fields? we are going to implement the same method, but this time we are going to use copper alloy nets.

In my opinion, I consider this the best solution and most practical solution out there.

By using this method, you are preventing the fish from reaching the area where the plant roots are floating. The final result would be an aquaponic system with fish and plants placed in the same unit without having to worry about any roots getting eaten.

Let’s say that you have a floating rack system with the fish living in it.

We will use the copper alloy net to separate the tank into two areas: The fish zone and the fish free zone.

You will cage a corner in the rack system with the appropriate area according to the number of fish that you have. Then, you will have to make sure that the copper alloy net is well placed from the surface down until it reaches the floor of the tank to prevent any fish from escaping into the fish-free zone.

3-Long Net Pots

The standard length net pots are the most commonly used in the hydroponic niche. Do you know that there are long net pots available in the market? These long net pots could be a good solution to protect your plant roots from getting eaten by fish.

By using these longer net pots, you are giving more protected room for the roots system to grow. However, the downside of this solution is that it is only effective until the roots reach a certain point where it exceeds the net pot’s parameter and the fish starts to have easy access.

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