Discus Fish Tank Lighting

Discus fish are very specific about their tank requirements and one of these requirements include tank lighting.

So, how exactly do discus fish prefer the lighting in their aquarium? Discus fish are more suited to darkness and demand a dim lighting usually for around 10-12 hours a day.

However, there are some technicalities involved with this kind of lighting strategy which we will cover below.

What kind of lighting do discus fish require?

A general rule of thumb for making the perfect aquarium for any fish is to always try to match the tank conditions to that of the fish’s natural habitat. The same goes for the lighting in your aquarium.

Discus fish, being freshwater fish and originating from the waters of the Amazon River, prefer a dimly lit environment with thick, dense plants. Because they live in such environments, it’s best to keep a steady hand on the lights you place in your tank.

Along with all of this, it is important to know that discus fish are used to sunlight. This means that they receive an average of around 10 hours or so of light; neither more nor less would satisfy their needs.

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The perfect lighting setup

Moving on to setting up the perfect lighting for these fish, our estimate of just the right amount of light for freshwater fish is around 1 to 1.5 watts of light per gallon. The light should be set on a timer for 8-10 hours a day at max. Along with all this, ensure that the tank is deep enough that the light spreads across it.

These lighting conditions perfectly mimic the discus fish’s natural habitat which allows them to remain healthy and stress-free.

More than that, make sure that the light temperature is somewhere around 6700K-10,000K. As far as the light itself goes, you can use any type you want, whether it be Halides, Fluorescent or LED fixtures. Halides and Fluorescent lights are usually the go-to solution for many aquarists due to their resemblance to natural light and their shimmering effect, but LED’s are a better choice if you are looking for a long-term solution. A major pro of using LED lighting is that it lasts for a much longer period and can be installed quite easily, unlike halides.

Lighting don’ts

Like everything else, there are certain things you should avoid at all costs when selecting the lighting for your aquarium. Firstly, just make sure that the lighting is not too bright.

As mentioned above, discus fish prefer a dimly lit environment and bright flashy lights and LED ornaments can stress out the fish quite easily. Live plants, on the other hand, require a lot of sunlight to grow and dim lighting will most probably retard their growth. To overcome this problem, either place artificial stones in the tank or provide it with enough light to suit both the plants and the fish. The artificial stones will allow the discus to hide when the light is too bright for them.

Due to dim lighting, you might also not be able to keep other fish who prefer bright lights. So, if you want more than one species of fish in your tank, try going for freshwater fish as they are suited to more or less the same environment as the discus fish.

How do tank conditions impact discus fish?

Discus fish are quite a challenge to keep, mostly because of their susceptibility to stress and diseases. These are caused usually by changing tank conditions which include lighting. These fish demand everything in a certain range, from water temperature to nitrate and nitrite levels for perfect health. Hence, if you’re planning to buy some discus fish, you should know how your tank conditions impact their health.

Most problems that aquarists encounter with their fish, whether they’re health problems or unusual behavior, is mostly due to the fish’s stress. Discus fish are particularly frail in this matter, and a sudden change in water conditions or their environment will drastically affect their health.

If you are planning on buying some of these fish, it is of utmost importance to always keep a check on the water conditions including ammonia, nitrate, and nitrite levels. Furthermore, keep an eye out for any sort of unusual behavior that your fish exhibits as it will help you identify diseases and health problems and get them treated quicker.

Decorations and ornaments

Lighting and Decorations enhance the overall look of your aquarium, as well as make the tank a cozier home for your fish. As far as lighting goes, we have discussed earlier that discus fish demand only dim lighting, but what about the tank decorations?

The perfect decorations and ornaments for discus and other freshwater fish consists of thick dense plants along with gravel and rocks. However, there are certain things that we recommend regarding these ornaments and some points that you should note before starting the decorating process.

As far as plants go, the discus fish comes from a generally dark environment with tall and thick plants. Due to this, placing dense plants will help you match the aquarium to their natural habitat. Be prepared to care for these plants as they can grow quite fast. Regular trimming after a week or two will definitely be sufficient.

Our recommendation is to place thick stem plants along with some driftwood. Driftwood not only looks appealing, but also softens the water pH to make the environment more livable for this particular species of fish.

For gravel and rocks, choose darker shades of both the ornaments. Avoid putting too much gravel in the tank as it will make the cleaning process quite harder. We would recommend you to skip on gravel altogether to help you with cleaning the aquarium. Such a tank is usually known as a “bared bottom tank” and works great for discus.

What water conditions suit discus fish?

Just like lighting, water conditions are perhaps the most important factor for healthy and stress-free fish. Discus fish, being delicate creatures, are more prone to rapidly changing water conditions as well as harsh lighting. These can put the fish in stress and make them vulnerable to diseases and health problems.

There are certain water parameters you should regularly check and maintain. These include the temperature, pH, and Hardness at the very basic.

Before you even put the discus fish in your tank, make sure that the water temperature is in the range of 382°F – 88°F (28°C-31°C). Be sure to keep the water as close to this range as possible to avoid stressing out the fish. You should also note that this temperature allows a relatively lower level of dissolved oxygen, which limits the fish you can keep in your tank.

As far as the pH goes, the ideal value is between 6 and 7. Any lower will stress the fish leading to health problems. The preferred hardness is 4DH, however discus fish will thrive in a hardness of anywhere between 1DH and 8DH as well.

Ammonia and nitrate levels

Discus fish are very receptive to ammonia and nitrite levels. Even the slightest amount can cause the fish to act strangely and loose color. It is always best to keep both ammonia and nitrite levels to 0ppm to avoid any sort of health problems within the fish.

An easy way to do this is to buy a cheap ammonia test kit from a pet store. Even though ammonia and nitrites convert into nitrates which is absorbed by the plants, you should always try and keep these parameters to zero. This can be done easily through regular water change. A 50% water change every week is enough to guard the fish from such problems.

The optimal tank for discus fish

As a fully-grown discus fish can get as big as 9 inches in length, they require a large tank to live. Before you set out to get your discus fish, make sure that the tank you have has a capacity of at least 50 gallons. As the fish are usually large in size, we recommend you to get a deep and long tank. Not only will this allow them to swim freely, but it will also get the light to spread evenly across the tank.

Moving on, you will also need to decide which type of substrate to place in the tank. The substrate allows plants to grow and bacteria growth in the tank. You can place whichever substrate you like, but if you want, you can also keep the tank bare bottomed. Keeping the bottom empty will have many benefits. Getting rid of the faeces and debris is easier when you have a bare bottomed tank. And when you regularly clean your tank, the water condition will always be up to the mark. All of this contributes to keeping your discus fish healthy.

Related questions

Where should light be placed in a tank for discus fish? The best position for placing lighting in a tank is on the ceiling.

What are the signs of a stressed discus fish? Discus fish can accumulate stress quite easily. Signs you should look out for comprise of color change, unfamiliar behavior, and irregular breathing.

What other fish can you keep with discus? Discus fish can be kept with different species of tetra fish such as neon tetras, rumy nose tetras, and rosy tetras.


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