Can Fish Feel Angry? A Surprising Fact about Underwater Friends



  • Fish can get Angry. The competitive environment is the main cause of aggressiveness in fish.
  • Food or shelter competition, territory and mates are common reasons why fish feel angry.
  • The angriest fish includes bettas, angelfish, bucktooth tetra and red devil cichlids.

Have you ever seen any images of angry fish on the internet? Or have you ever played the angry fish game? Then you can imagine the aggressive fish.

Can Fish Feel Angry? It may sound like something out of a children’s book, but the reality is that fish do feel a wide range of emotions, including anger. But not in the same way as the portrait shows.

Then, how do angry fish look and how can you feel the anger of your aquarium fish? Read this blog post and you will get the answer.

Can Fish Feel Angry? – Yes, They Do

Several fish shows aggressive behavior in certain conditions, such as when kept in a small tank or aquarium. Anger has a negative effect on fish.

Fish may become angry due to food or shelter shortages or a competitive environment. The environmental resources decide whether fish would be happy or angry.

Fish shows aggression in a competitive environment. According to Ronald G Oldfield in Aggression and Welfare in Common Aquarium Fish, the Midas Cichlid, the aggression may be lower in the larger fish tank.

According to a new study, there is a risk that all of the ornamental fish in the United States may become aggressive due to the barren or unnatural aquarium environment.

Aggression in ornamental fish is increasing which is a sign that fish can feel angry.

Therefore, fish should be kept in a larger tank and natural habitat should be provided.

Why do Fishes Have Feelings of Anger?

If you want to calm and control the aggressive behavior of fish, then it is necessary to be aware of the reasons for anger.

Various factors trigger anger in fish. Let’s discuss them.

1. Food Competition

Food shortage is one of the fish’s leading causes of stress and anxiety. When fish are not able to find enough food, they become aggressive.

The competition for food increases among fish. This competition leads to aggression that ultimately results in fighting. Due to aggression or fighting, serious injuries or the killing of fish occurs.

2. Territory

Several fish creates their territory. Aggressive fish such as betta keeps themselves in their environment. Territorial fish exhibits a higher level of aggression than non-territorial.

Betta fish feel angry when their territory is threatened - Can fish feel angry?

In aquarium or wild, these fish limits themselves to their territory. As a result, when other fish invade their territory, they become aggressive.

3. Mates

Some owners add new female fish into the tank. Due to this, already present female or male fish may get angry with new ones.

The angry behavior could be observed in their swimming pattern. Aggression could be so severe that it may lead to a fight.

How Do You Know When A Fish is Angry?

Several indicators show your fish is angry. Your fish may not be as chill as you think, and it’s essential to keep an eye on their mood swings. Otherwise, the aggressive behavior of fish may cause a fight in your aquarium.

If your fish has been hiding in the bottom of their tank all day and you can hear them growling under their breath, they might be getting ready to attack.

Betta fish flare up their gills when they are angry. Betta spreads fins and their swimming pattern gets irregular in the tank.

Aggression or anger could easily be seen in the fish, and their physical appearance shows it.

Do You Know the World’s Most Angry Fish?

Some fish have aggressive behavior naturally. These fish includes Tetra, Bettas, Veil Angelfish etc.

1. Bettas

Bettas are the fighting fish. Whenever these get threatened, they show aggressive behavior. These are self-sufficient and don’t interact with other fish. Therefore, avoid keeping betta with other small fish or innocent guppies.

2. Angelfish

Angelfish is a schooling fish, but the fish in schools might fight with each other for dominance. Changing water conditions may alleviate aggression in these fish. Therefore, you should change the water less frequently.

3. Bucktooth Tetra

It is thought to be one of the angry fish. It bites other fish of the same or different species with its front teeth.

If you want to keep these fish in an aquarium, you must take a group of tetras and don’t keep it with other fishes. In this way, the probability of fighting would be less.

4. Red Devil Cichlids

These are territorial and aggressive fishes. They may attack other fish if they invade their territory.

Red devil fish can also feel angry when their territory is threatened.

These fish may destroy decorations or other things in the aquarium. It is recommended not to keep other fish with the red devil.


It is a well-known fact that fish are highly territorial creatures. They are constantly fighting for dominance over their territory. This fight for territory can often lead to aggression.

Food shortage or survival may also be the reason for anger in fish. Some fish have naturally aggressive behavior.

If your fish get angry, what are the possible reasons for their anger? Leave a comment below.


  1. Aggression and Welfare in a Common Aquarium Fish, the Midas Cichlid by Ronald G. Oldfield –
  2. Ornamental Aquatic Trade Association
  3. Poncin, P., Matondo, B. N., Termol, C., Kestemont, P., & Philippart, J. C. (2011). Relationships between circulating androgens, aggressive behaviour and breeding tubercles in males of the common bream Abramis brama L. in an aquarium environment. Fish physiology and biochemistry, 37(3), 533-542.
  4. Saxby, A., Adams, L., Snellgrove, D., Wilson, R. W., & Sloman, K. A. (2010). The effect of group size on the behaviour and welfare of four fish species commonly kept in home aquaria. Applied Animal Behaviour Science, 125(3-4), 195-205.

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