Are Discus Fish Aggressive? [Ways To Deal With Their Aggression]

Are Discus Fish Aggressive? [Ways To Deal With Their Aggression]

Discus fish getting aggressive

Discus fish aren’t aggressive. However, they can get aggressive while pairing up for spawning. Other reasons why discus can get aggressive are inadequate food, overcrowding, small group, and unfavorable tank conditions. Providing a favorable environment with adequate food can curb their aggression.

Let’s now learn more about the various reasons for discus aggression and effective ways to stop it.

Are Discus Fish Territorial?

Similar to cichlids, discus can get territorial to establish a pecking order.

The most dominating discus fish is at the top of the order, followed by others.

Once the pecking order is established, discus usually don’t get aggressive.

They also don’t bother other fish in a community tank.

Discus can also get territorial when they breed. It’s because of their nature to protect their eggs.

By being territorial, discus ensure that their eggs hatch and fry get born.

They display the same behavior even in their natural environment.

Why Do Discus Fish Get Aggressive?

Discus is one of the peaceful fish among cichlid species.

However, it’s also vital to remember that they display an aggressive temperament when necessary.

Given below are some of the prominent reasons for discus fish aggression.

Pecking Order

A strict pecking order gets formed when discus fish are housed together.

The dominant fish will always have its territory at the top of the hierarchy.

The aggression to establish a pecking order usually lasts only for a short time until the order is set.

Once it’s done, there’s no more fighting.


Discus fish are generally calm and peaceful. However, there are always some fish that are more dominant than others.

The dominant discus will try to intimidate the other timid discus fish by fighting with them.

It will establish dominance over the rest by displaying aggression.

Breeding Season

Discus fish are known to get aggressive, especially when attempting to pair up and spawn.

Usually, when two discus fish pair up, they can become aggressive toward the other fish in the tank to secure their territory for laying eggs.

The male discus becomes explicitly aggressive toward the other males to protect its mate.

On the other hand, the female discus fish can get highly aggressive while guarding her eggs.

Also, if there are fewer females in the tank, the male discus fish can start fighting with each other over the female discus fish for mating purposes.


Overcrowding is another reason for discus fish to become aggressive.

When there are too many discus fish in a tank, it will lead to space constraints.

Discus fish need ample space to swim freely. Shortage of space can irk them, leading to aggression.

Territorial issues can also arise between them as discus fish can encroach on each other’s territories due to cramped space.

Food Scarcity

Every fish needs adequate food to thrive. If there’s food scarcity, all the fish will start competing for the limited food supply.

Hunger can lead to aggression toward each other for food consumption.

In such cases, the timid discus fish will suffer the most as they will be deprived of food.

Unfavorable Tank Conditions

Discus fish in favorable tank conditions

Discus fish need favorable tank conditions for healthy development.

If the conditions aren’t conducive, it can lead to stress.

A stressed discus is more likely to display aggression since it’s in discomfort.

Poor water conditions, incorrect water parameters, lack of adequate space, food scarcity, and absence of enough hiding places can stress the discus fish, leading to aggressive behavior.

Small Group

Discus fish thrive when kept in a group of 6 or more. If they’re kept in a small group in captivity, they may display aggression.

The dominant discus fish may assert dominance over the timid fish by being aggressive.

The size of the fish should also be considered while keeping a group of discus fish.

It’s recommended to house similar-sized discus together.

If a large-sized discus is housed with smaller ones, it can lead to bullying.

Can The Aggression Of Discus Fish Be Fatal To Each Other?

Discus fish don’t fatally injure each other. However, they can become aggressive, especially during the mating period.

The probability of discus fish severely injuring each other during the breeding season is less if the fish count is more.

Although discus fish don’t fatally harm each other, they may hurt other fish in aggression.

It’s normal behavior. However, it can prove fatal if the other fish get severely injured.

Fish can also get stressed during the breeding season.

Stress can weaken the immune system, making them more prone to diseases.

It can lead to the untimely demise of the fish if immediate action isn’t taken.

So you should take care during such times. The more relaxed your fish is, the healthier it will be.

How To Deal With Aggressive Discus Fish?

Discus fish have a reputation for being peaceful compared to some of the other cichlid species.

However, they can display aggression if certain conditions aren’t met.

Given below are various ways to reduce discus fish aggressiveness:

  1. Keep discus fish in tanks with enough space to move around.
  2. House discus fish with tankmates of similar size and temperament. If one fish is larger than the other, it will become aggressive and start to dominate the smaller tankmates.
  3. Provide sufficient food to all the fish in the tank. You can spread the food in different portions of the tank so that all fish get an opportunity to eat.
  4. Avoid overcrowding the discus tank. This can cause stress which leads to aggression. If there are too many discus fish, the tank should be larger.
  5. Provide plenty of hiding places so that discus fish can hide if they feel threatened. Caves, rocks, plants, and driftwood are ways to provide shelter to fish.
  6. Ensure ideal water parameters to curb aggression.
  7. Build a well-designed aquarium to keep the discus fish happy and healthy.
  8. Keep the discus fish in a group of at least six or more.
  9. If there’s a dominant discus continuously bullying the other tankmates, separate it from the others. After some time, you can put the fish back to check if it has mellowed down.
  10. If you house discus in a community tank, make sure that the tankmates are compatible.
  11. Male discus can become aggressive during the mating period. So limit the male discus fish count in the tank to curb the aggression.
  12. Keep enough female discus in the tank for every male discus. The ideal ratio of male to female discus is 1:3.

Even after taking all the necessary precautions, if your discus fish start showing signs of aggression, then it’s best to seek help from a veterinarian.

Is Female Discus Aggressive?

Female discus fish are peaceful. They’re less aggressive compared to male discus.

But they can become aggressive while guarding their eggs.

Like male discus fish, females also like to establish a hierarchy to claim their territory.

However, their fight is less violent than males. So the chances of any fish getting injured severely are minimal.

Female discus can also become aggressive if male discus continuously harass them for mating purposes.

So it’s crucial to have more female discus fish in the tank so that no single female is troubled.

Female discus fish can also get aggressive when the tank conditions are not conducive, the tank is overcrowded, or there’s food scarcity.

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