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The Discus is one of the most elegant and sought-after aquarium fish with its striking colors and calm nature. Generally, they are peaceful and social, though in a few rare scenarios, and of course being part of the cichlid family, some aggression has been reported, mostly among its own species.

Though not entirely in their nature, it is crucial to fully comprehend the intricate care needs, and nature of the Discus to address the issues of aggression, as well as to prevent any chances of aggressive behavior.

Discus Species Information

The Symphysodon, or as it is informally known the Discus is a class of cichlid species. Cichlids as a family of fish species, especially African origin Cichlids are notorious for being very aggressive. However, the Discus is one of the more peaceful and passive Cichlids species originating from the Amazon River basins in South America.

Discus fish have a very distinctive shape, with bright colors and patterns, as well as remarkable behavior, making them popular in the aquarium trade. They are quite striking and popular among international breeders and collectors, especially as show breeds for their elegance and intriguing colors. It can be found that some Discus variations and colors are rare and expensive.

Though found in both blackwater and white water bodies naturally they are known to prefer lentic habitats (still water), including flooded plains and forests with mostly white water that has suspended materials, rather than rivers and streams.

It is important to understand though, according to many experienced breeders that the Discus is a fish species more suited to advanced aquarists that have the knowledge and resources for their strict care requirements in terms of water quality and aquarium set-up. Furthermore, the Discus is a larger fish as an adult growing to between 8 and 10 Inches (20-25 cm), that needs to be kept in groups of its species, meaning a substantial-sized tank will be required. Similarly, they have a long lifespan of between 10 and 15 years with proper care.

A Few Interesting Facts About The Discuss

• The Discus is referred to as the “King of the Aquarium Fish”.
• It forms part of the Cichlid family, however is more peaceful than most species from this family.
• The Discus is a unique Cichlid from America that prefers to be in groups of its species.
• When a Discus experiences extreme emotions, especially fear, the color of their skin will become much brighter.
• They are ideally mostly carnivores, though quite peaceful and not cannibalistic towards their young.
• They are relatively slow swimmers, hence why they prefer staying in groups.
• The Discus requires extremely clean and warm water and can be sensitive to changes in water parameters.
• Discus fishes are naturally superb parents, couples will separate from the group and males and females take care of their young.
• The female Discus secretes a “Discus Milk” from her skin to feed her young during the first 4 weeks.
• Male Discus fishes are contrarily larger than females.

What Does A Discus Look Like

The Discus has a laterally compressed body with a rounder shape than most Cichlid species, hence why it is known as a “discus” fish. It has more extended fins, and patterns on the body that are typically shades of red, brown, green, or blue. Due to selective breeding, more brightly colored variants are available that do not naturally occur in the wild. As mentioned the Discus can change color, especially when experiencing certain emotions, becoming much brighter and bold in color.

Some of the most common colors bred in the aquarium trade are:

• The Red Turquoise Discus
• White Dragon Discus
• Golden Calico Discus
• Heckel Cross Discus
• Blue Scorpion Discus
• Cobalt Blue Discus
• White Diamond Discus
• Albino Millenium Golds
• Mercury Discus
• The Red and Orange Pigeon Blood Discus

Discus Behaviour And General Temperament

In comparison to other Cichlid species, Discus fishes are relatively calm, peaceful, and slow-moving fish, however, they can become slightly aggressive especially when spawning, and may pick on weaker fish of their species.

Generally known to be social and having a preference to congregate in groups, Discus fishes similarly are excellent parents, both taking care of their young until they are independent enough to fend for themselves.

Discus fishes are prone to bullying from other more competitive fish species and are well known to become stressed easily when kept with more aggressive or territorial fish species.

Caring For A Discus

It is vital to cater to the very specific care needs and water conditions of a Discus for it to flourish, as they can be relatively sensitive. By managing water parameters and keeping their aquarium in pristine conditions, it is easy to successfully keep Discus fishes. Keep in mind that they are kept in groups of four or more to feel safe and stay calm.

• Setting Up an Aquarium – A large tank of between 55 – and 75 gallons will be required for a group of four or more Discus fishes. Similar to their natural environment the Discus prefers water with a low current that is clean and clear, thus taking care when purchasing a filter. Most hang-on back filters are ideal. They prefer more tropical climates and higher temperatures of around 26 to 30°C between (80° and 86° F), except the Heckel Discus species that prefer slightly higher temperatures of around 32°C (90° F). A water pH of between 6.0 and 7.5 is suitable, and they prefer moderately soft water conditions, ideally, water that has undergone Reverse Osmosis (OR) treatment, with additional salts and minerals, is advised by most knowledgeable Discus keepers. Generally, Discus fishes prefer a more natural environment with plenty of open space for swimming, additional rocks, driftwood, and a few live plants.
• Feeding – as mentioned and according to various studies, the Discus is said to be an omnivore, because it will feed on algae and certain plant materials, though they are mostly carnivorous. A diet rich in protein-based foods such as specific Discus flakes, Shrimp, Bloodworms, Insects, and larvae is advised, along with algae rounds and corn flakes.
• Regular Tank Maintenance – Additionally tank cleaning and maintenance are vital when keeping Discus fishes, they need clean and clear water with optimal parameters. It is advised to regularly replace tank water by siphoning at least 25% of the water from the bottom and replacing it with clean OR, and conditioned water that is the proper climate. Maintenance is advised at least once a week.
• Breeding – Though adult male Discus fishes are larger than females there are almost no discernible differences in them besides their genital papilla. The Males have pointed longer genital papillae, while the females are more rounded. Keeping a group of Discus fish will ideally enhance the chances of having males and females that will eventually pair off by themselves during the spawning season. Mated pairs will become more territorial and claim a space to lay their eggs, usually low on the ground. You can use PVC Pipes or terracotta pots to create a safe environment for laying eggs. Discus fishes as mentioned earlier are nurturing parents that will take care of their young. You can feed them baby brine shrimp as soon as the fry starts swimming independently.

Common Health Issues

In peak conditions Discus fishes will thrive and remain essentially disease free, though there are a few common health conditions that may affect them:

• Internal Parasites – One of the most common internal parasites that are prone to affect a Discus is Hexamita, a small parasite infecting the small intestines. Symptoms include white excrement, fish losing weight, or a hole in their head. The parasite can easily be treated with Metronidazole, according to specifications given by a vet. Discus fish rarely contract other worms or parasites, such as tapeworms.
• Cloudy Eyes – A very common ailment that is prone in Discus fishes is called Cloudy eyes. Usually, physical damage to the eye or a sudden crash in the pH balance of your tank are the culprits. Luckily the condition is easily treated with salt or medication containing Aloe Vera.
• Fin Rot – Fin Rot is a common condition in most freshwater fish species, as a result of a bacterial infection, because of damage or injury to the fins of the fish. By placing the fish in a quarantine tank with clean water, and using a broad-spectrum antibiotic the condition should clear up easily.
• Bloating – Just as humans are sometimes prone to becoming bloated because of excess gas in the stomach or being constipated, Discus fishes can similarly suffer the same symptoms. The easiest treatment is to add a tablespoon of Epsom salt per 40 liters in your tank and raise the temperature slightly. The treatment will increase the metabolism of your fish, and you may notice some excess excrement in the tank, in which case after a few days a proper water cycle will be required. Adding a mild metronidazole treatment to the water will help in case the Hexamita parasite decides to develop in the excrement of your fish.

Discus Fish Are They Aggressive And Why?

Finally, after getting to know a bit more about the Discus and its care requirements, the topic of whether they are aggressive can be understood in more detail. Over many platforms, Discus fishes are explained to be Peaceful and social fish that are rarely prone to aggression in contrast to other cichlid species. Though there is somewhat more to be said about aggression in Discus fishes.

Are Discus Fish Aggressive?

To answer the question, according to many studies, Discus fishes are one of the most peaceful fish species from the cichlid family but keep in mind they are still cichlids that do carry the general temperament of becoming aggressive at times.

Aggression in freshwater fish can mostly be noted when fish chase each other, or slap their bodies against each other, and pick at each other. In most cases healthy fish tend to pick on weaker or ill fish to remove the “weaker links”, and ill fish will tend to be more shy and sluggish.

The best way to prevent aggression in Discus fish is to always keep them in larger groups.

If there still seems to be aggression in Discus fishes, towards each other, or other fish species in the Aquarium, there are a few reasons that can indicate why:

• Pecking Order – Discus fishes what is called a pecking order (hierarchy), in which you will have dominant and more submissive individual fish in the group. Adding a group of young Discus fishes may take some time to establish a pecking order, though with mature Discus fishes there may already be a well-established pecking order. Adding a mature Discus to an aquarium with younger ones, or adding a new Discus to a group may interfere with the pecking order and cause aggression.
• Dominant Behaviour – In some cases there may be a more dominant individual Discus that will show aggression towards the other more timid Discus fishes to establish dominance.
• Spawning and Breeding – During Spawning males become aggressive towards other males to secure their partners. Females may become aggressive in trying to protect their eggs. In the case of a tank with fewer females than males, the males may fight over suitable females.
• Territory Conflict – Naturally Discus fishes will be territorial when breeding protecting their space. They are usually only aggressive towards fish of their species.
• Lack of Space – When too many Discus and other fish species are kept in a tank, it becomes overcrowded, and territorial issues may become more prominent, causing aggressive behavior.
• Food Fights – A hungry Discus will become aggressive and compete for food, and the stronger more dominant fish may eat all the food leaving the weaker few to be deprived.
• Poor Aquarium Conditions – Poor water conditions that do not fit the correct parameters can quickly cause stress in Discus fishes, which may lead to some form of aggression.
• Incorrect Ratio – Discus fishes are known to thrive in groups, the smaller the groups the more aggression may be noted. It is always advised to keep groups of between 4 and 6 that are within the same age group or relative size.

Dealing With Discus Fish Aggression

• Feeding – When feeding, spread the food around all over the tank so that each Discus and other fish species can get enough to eat.
• Changes to Aquarium – If aggression is noted for no apparent reason, you can try to change the tank around, which will break down territories, and keep them from fighting.
• Add More Fish – Larger groups of Discus fishes do not tend to display aggression. Ensure that they are obtained in a group, and are around the same size.
• Newcomers – Your Discus fishes may not take kindly to single new Discus fishes added to the tank, especially if they are younger. Rather add all your Discus fish at once.
• Tank Size – Ensure that the aquarium is the correct size for your Discus group and other fish species as a lack of space can cause much stress.
• Breeding – You may try to separate breeding pairs into a separate breeding tank to avoid aggressive behavior towards other fish during this time.

Thus, when kept in larger groups, with ample space and proper water conditions, your Discus fish should get along quite peacefully. If they are well-fed and have space for breeding territory, fighting and aggressive behavior may similarly be reduced.

Discus Fish And Aggression Towards Other Fish

The Discus is noted for its tranquility, and peaceful nature, especially towards other fish species. There is generally a greater chance of a Discus being bullied by larger more aggressive fish species.

According to studies the only times aggression was displayed by Discus fishes towards other fish species were during breeding, to protect their territory. Good advice is to add your Discus group to an aquarium already established with other companion species or to add all species at once, as Discus fishes tend to form a pecking order and may show slight aggression towards newcomers.

What Are Other Suitable Fish Species As Companions?

On the topic of Discus aggression towards other fish species, there are a few peaceful species that will easily get along with Discus fishes, without any aggressive behavior:

• Corydoras Sterbai – They are peaceful bottom feeders that clean the bottom of the tank.
• German Ram – A Dwarf Cichlid species that will add a splash of color to your aquarium and get along with the Discus fish.
• Marbled Hatchetfish – Calm and peaceful bottom feeders that enjoy some floating plants to hide in.
• Rummy Nose Tetras – They are small and eye-catching with a similar diet to that of the Discus.
• Harlequin Rasbora – Both attractive and very calm fish species.
• Siamese Algae Eaters – Bottom-feeding algae eaters that will not compete with a Discus for food.
• Rainbow Fish – When kept in larger groups, they are striking and calm.

In The End

A tank with a group of Discus fishes of around the same size, and a few other peaceful community fish is a much more balanced and calmer environment for your Discus fishes. There is not much to be troubled about concerning aggression in Discus fishes, they are well known for being peaceful, and it is only in a few rare cases where some aggression is noted.

Frequently Asked Questions