Lighting for Aquaponic Fishes: Do They Actually Need it?

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In aquaponics, fishes provide nutrients for plants to grow by bacteria breaking down ammonia from their waste into nitrates which is then used by the plants. It’s essentially a closed loop ecosystem created by the symbiotic relationship between plants and fishes. 

Aquaponic Fishes can function with up to 18 hours of light to carry out their daily functions as living organisms. Light is a necessity for aquaponic fishes and helps contribute to their health, stress levels and reproductive functions. 

Fishes are the driving force of an aquaponic system; they provide the source of nutrients which plants use. Healthy fishes produce healthy nutrients. 

And Healthy fishes are based on how well they thrive in their environment. The amount of light provided for the fishes can affect their health and how they function. 

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Do Fishes actually need light?

The fact that the eyes of common fishes like tilapia, perch and koi are relatively large says much about their evolution. These fishes have these eye structures because they use it for survival in the wild. 

Fishes need light to carry out their daily functions.

The conditions in an aquaponic system is not anything close to conditions these aquatic animals may be subjected to in the wild. 

Fishes need light to see their food. 

Housed in a closed environment with many other fishes, being able to see the food when it’s available is a part of survival in an aquaponic system for fishes. 

Without light the fishes would have a hard time finding food which in turn of left uneaten can lead to fouling of the system. Therefore, the more light fishes are exposed to tend to increase their growth rate since they are able to feed more with the available light.

The reproduction of fishes would fall drastically since fishes will not be able to carry out the function. 

Have you ever seen the courting ritual of the male and female tilapias? They are very playful and territorial around this time. Without light these attributes of reproduction would cease and the cycle itself would not occur.

How does light affect the Health of the fishes?

Light is required for body pigmentation especially during early development of fishes. This is true for most fishes especially colorful fishes like kois and tetras. 

High intensity light can be stressful or even lethal to fishes.

How much light does aquaponic fishes need?

Reproduction and spawning are best achieved with a photoperiod of 18h and 2500 Lux light intensity. Meaning that the fishes can perform well with a light period of 18 hours a day. 

Source –

Lux is the SI derived unit of illuminance, and is equal to one lumen per square meter.

What types of light are best for aquaponic fishes?

The type of light that fishes are subjected to are produced different outcomes when it comes to reproduction. 

The species under speculation is the blue Nile tilapia because it’s the most commonly used fish in aquaponics due to their growth and reproduction rate. 

Blue environmental color influences fish reproductive behavior. The higher reproductive rate and more intense nesting behavior in groups under blue light strongly suggest that this light stimulates reproduction in Nile tilapia.

Source –

Blue light comes mainly from light in the range of 5000k and 6000k, light intensity. 

The light spectrum ranges from 1000k to 10000k where 1000k is the dimmest light and 10000k being the brightest. 

From the same study listed above it was concluded that fishes perform better and produced less stress hormones when subjected to living in a green environment. 

I think mostly it’s from their nature and being surrounded by green plants calms their behavior since they have a more homey feeling. 

It’s only natural to feel at home if your are surrounded by the thing you are accustomed to. 

Apparently these fishes are no different and the benefits can be seen from their low stress levels and reproductive responses when around these calming colors.

What Type of light Should you Use for Fishes?

LED lighting is the best kind of light which should be used for fishes. LED or Light Emitting Diode, are very efficient and most beneficial when compared to other light sources.

If you have to keep the light on for a 18 hour period the power consumption over time would certainly add up. LEDs are very energy efficient and long lasting.

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Apart from the power aspect, Other light sources can add unwanted heat to the aquaponic system which brings a lot of negative side effects such as decreases dissolved oxygen and pH swings.


JayLea has a passion for plants and has been gardening since 2015. He has valuable knowledge about gardening and houseplant care and can answer everyday practical questions that every plant owner has.

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