Do Fish Get Sad When Other Fish Die? Unbelievable Study

Have you ever wondered what happens to a fish when its tank mate dies? It’s a curious question and one that might have crossed your mind as an aquarist. This blog post is here to delve into the emotional responses of fish, specifically their potential feeling of sadness when they lose a companion from their aquatic home.

Stick around – we’re about to plunge deep into the undersea world of fish emotions.

Key Takeaways

  • Fish lack the emotional capacity to experience sadness when other fish die, as their brains are not structured to process emotions in a complex manner.
  • Fish do not understand the concept of death and primarily focus on their own survival and well-being.
  • While fish may exhibit changes in behavior and appetite when a tank mate dies, these responses are more likely due to stress or disruption in their social dynamics rather than genuine sadness.
  • It is important for aquarists to monitor and support the remaining fish after the death of a tank mate by maintaining proper tank conditions, providing enrichment and stimulation, and introducing new tank mates gradually.

Do Fish Get Sad When Other Fish Die?

Fish do not possess the emotional capacity to experience sadness when other fish die, as they lack the understanding of death and possess primarily survival instincts.

Lack of emotional capacity

Fish lack the emotional capacity that mammals or birds possess. They don’t experience sadness, grief, or mourning as we humans understand them. This is primarily because their brains aren’t structured to process emotions in such a complex manner.

Their instinctual survival mechanisms surpass any potential sentimentality. It’s important to note that while some fish may display behavioral changes after losing a tankmate, this shouldn’t be interpreted as an emotional response akin to human grief but rather related to alterations in their environment or social dynamic.

For instance, pair-bonded fish could exhibit signs of distress when separated from their mate; however, it doesn’t indicate they are mourning the loss. Researchers have found no evidence supporting the idea that fish recognize impending death among fellow species members either.

Lack of understanding of death

Fish lack the understanding of death. Unlike humans, they don’t comprehend the concept of mortality. While fish can sense danger and strive to survive, their understanding is limited to immediate threats like predators or changes in their environment.

They do not possess the cognitive ability to grasp that a fellow fish has ceased to exist permanently. Instead, their main focus is on maintaining their own survival and well-being.

So while it may seem like they are indifferent when another fish dies, it’s important to remember that this behavior stems from their instinctual nature rather than emotional comprehension of death.

Survival instincts

Fish have evolved with strong survival instincts that prioritize their own well-being. While they may not experience emotions like sadness or grief when another fish dies, they do recognize the need to survive and live.

In the wild, this instinct helps them navigate dangers and find food. Even in a controlled aquarium environment, these survival instincts remain intact. Therefore, it is important for aquarists to provide their fish with proper tank conditions and care to ensure their overall wellbeing and minimize any potential negative impacts on their behavior.

Maintaining good water quality, providing enrichment and stimulation, as well as introducing new tank mates gradually are all ways to support fish in dealing with death or changes in their social dynamics without relying on emotional responses that they simply do not possess.

Responses of Fish When Another Fish Dies

When another fish dies, fish may exhibit changes in behavior and appetite, as well as experience potential impact on their social dynamics.

No mourning behavior

Fish do not exhibit mourning behavior when another fish dies. Unlike humans, fish lack the emotional capacity to understand and experience grief. While some fish may display changes in behavior and appetite after a tank mate’s death, these reactions are more likely due to stress or disruption in their social dynamics rather than genuine sadness.

Fish primarily rely on survival instincts and maintaining their own well-being, so mourning the loss of another individual is not a part of their natural behavior.

Potential changes in behavior and appetite

  • Fish may exhibit changes in their behavior and appetite when a tank mate dies.
  • Some fish may become more aggressive towards other tank mates or show increased territorial behavior.
  • Others may become withdrawn and less active, spending more time hiding or staying in one area of the tank.
  • Loss of appetite is a common response to the death of a tank mate, with fish refusing food or showing reduced interest in eating.
  • These behavioral changes can vary depending on the individual fish’s personality, species, and previous social interactions.
  • It’s important to monitor these changes closely and ensure that they are not due to any underlying health issues or poor water quality.

Impact on social dynamics

The death of a fish in your tank can have a significant impact on the social dynamics within your aquatic community. Here are some ways in which other fish may be affected:

  1. Increased aggression: The loss of a dominant or territorial fish can cause a power vacuum within the tank, leading to increased aggression among the remaining fish as they compete for dominance.
  2. Altered hierarchy: When a higher-ranking fish dies, the social hierarchy within the tank may shift. The remaining fish will need to establish new pecking orders and adjust their social interactions accordingly.
  3. Behavioral changes: Fish may exhibit changes in behavior after the loss of a tank mate. They may become more withdrawn, less active, or display abnormal swimming patterns. These changes could be indicators of grief or stress caused by the absence of their companion.
  4. Decreased appetite: Fish that were closely bonded with the deceased may experience a decrease in appetite due to the emotional impact of the loss. This can result in weight loss and weakened immune systems, making them more susceptible to illness.
  5. Reduced socialization: In some cases, fish that lose a companion may become less inclined to engage in social interactions with other tank mates. They may spend more time hiding or avoid areas where they previously interacted with their deceased companion.

How to Support Fish in Dealing with Death

To support fish in dealing with death, it is important to maintain proper tank conditions and provide enrichment and stimulation. Additionally, introducing new tank mates gradually can help alleviate any potential loneliness or stress that may arise from the loss of a companion.

Want to learn more about how fish respond to the death of their tank mates? Read on!

Maintain proper tank conditions

To ensure the well-being of your fish and help them cope with the loss of a tank mate, it is crucial to maintain proper tank conditions. Here are some important tips for creating a healthy environment:

  1. Provide clean water: Regularly test the water parameters such as pH, ammonia, nitrite, and nitrate levels. Use appropriate filtration systems and conduct water changes as needed to keep the tank environment clean and stable.
  2. Optimal temperature: Different fish species require different temperature ranges. Research the specific temperature preferences of your fish and ensure that the aquarium heater is set at the appropriate level to maintain a stable temperature.
  3. Proper nutrition: Feed your fish a balanced diet that meets their nutritional needs. Overfeeding can lead to poor water quality, so be mindful of portion sizes and remove any uneaten food from the tank.
  4. Sufficient space: Make sure your aquarium provides enough space for all the fish to swim comfortably and establish territories. Overcrowding can cause stress and aggression among the fish.
  5. Hideouts and structures: Create an enriched environment by adding plants, caves, or decorations that allow fish to hide or seek refuge if needed. This helps reduce stress levels and promotes natural behavior.
  6. Regular maintenance: Clean the tank regularly by removing debris, algae, and uneaten food. This helps prevent water quality issues and ensures a healthy living environment for your fish.
  • Fish keeping guidelines from reputable aquarist sources

Provide enrichment and stimulation

To support fish in dealing with the death of a tank mate, it’s crucial to provide them with enrichment and stimulation. This can help alleviate any potential sadness or loneliness they may experience.

One way to do this is by offering different types of hiding places, such as caves or plants, where fish can explore and seek shelter. Changing up their environment occasionally with new decorations can also keep things interesting for them.

Additionally, introducing toys or objects that they can interact with, like floating toys or mirrors (used sparingly), can stimulate their natural behaviors and prevent boredom. Providing a variety of food options will not only ensure their nutritional needs are met but also give them mental stimulation as they search for and consume their meals.

Introduce new tank mates gradually

Introducing new tank mates to your fish should be done gradually to ensure a smooth transition and minimize stress. Here are some tips on how to do it:

  1. Quarantine new fish: Before adding them to the main tank, quarantine new fish for a few weeks in a separate tank. This helps prevent the spread of diseases and allows you to observe their behavior and health.
  2. Observe compatibility: Research and choose fish species that are compatible with your existing tank inhabitants in terms of water parameters, temperament, and size. Some fish may be aggressive towards others or have specific compatibility requirements.
  3. Acclimate slowly: When it’s time to transfer the new fish into the main tank, acclimate them slowly to minimize stress. Float their bag in the tank for about 15 minutes to allow them to adjust to the temperature. Then, open the bag and let some water from the tank gradually mix with the bag water over another 15 minutes before releasing them.
  4. Rearrange decorations: Rearrange decorations in the tank before introducing new fish. This helps disrupt territories and prevents aggression from established members feeling threatened by newcomers.
  5. Feed well: Ensure all fish are well-fed before introducing new ones as hungry fish can become more aggressive towards potential rivals.
  6. Monitor interactions: Keep an eye on interactions between existing and new fish for signs of aggression or stress. If any issues arise, be prepared to isolate or remove certain individuals if necessary.
  7. Maintain good water quality: A clean and stable environment is crucial when introducing new tank mates as fluctuations can cause stress or illness. Regularly test water parameters, perform regular water changes, and provide appropriate filtration for optimal conditions.


In conclusion, while fish may exhibit some behavioral changes when a tank mate dies, they do not possess the emotional capacity to experience sadness as humans do. Their responses are more closely tied to survival instincts and changes in social dynamics rather than grief or mourning.

As responsible aquarists, it’s important to focus on maintaining proper tank conditions and providing enrichment for our fish’s overall well-being.


1. Can fish experience sadness when other fish die?

While it is difficult to determine whether fish experience emotions like sadness, studies have shown that they do exhibit behavioral changes and responses when faced with the death of other fish in their social group.

2. What are some signs that indicate a fish may be affected by the death of another fish?

Signs that a fish may be affected by the death of another include decreased appetite, lethargy, hiding or isolating themselves from other tankmates, and changes in swimming patterns or behavior.

3. How can I support my remaining fish if one dies?

Providing a stable and comfortable environment for your remaining fish can help alleviate any potential stress caused by the loss of a tankmate. This includes maintaining proper water quality, ensuring adequate space and hiding spots, and monitoring their behavior closely for any signs of distress.

4. Should I replace a deceased fish immediately with a new one?

Introducing a new fish immediately after the death of another can disrupt the existing social dynamics within your aquarium. It is recommended to wait until any potential causes of illness or aggression have been addressed before considering adding a new member to your aquatic community.

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