Having a death in your fish tank is horrible for any fish owner. You wonder if it was your fault, and what you could have done to avoid it. While you may be mourning the loss of your fish, what about the other fish in the tank? And what about fish in the wild?
That’s what we’re going to find out here. It has been shown that many animals mourn their dead, but these are usually animals with more complex brains such as primates, elephants, and dogs. Let’s check out if fish mourn their dead.
The Concept of Mourning in Animals
Mourning is described as a behavioral and emotional response to loss. This is common in mammals such as elephants and will be associated with behaviors we are familiar with such as depression, social withdrawal, and death rituals.
The problem with mourning is that it’s complex and difficult to measure. This is the same in humans. Whereas someone may be in floods of tears, someone with the same level of grief may internalize their pain instead.
With fish, this difficulty comes from their lack of facial muscles and vocal cords. If a fish is sad, we can’t see it through still observation. That may be true, but we do know that fish will exhibit different behaviors if they are stressed or anxious.
Social Bonds Among Fish
Another complexity of this question is the sheer variety of fish. Some are solitary and are happy to live their whole lives alone, whereas others will want to be in pairs, small groups, or even large schools.
Strong evidence that fish care about others is monogamous pairing fish, such as cichlids. They have been shown to not only pair with just one fish but also cooperate with parental responsibilities. This also makes cichlids one of the best options if you want a fish you can form a bond with.
Following such loss, changes in behavior can often be observed. The tricky part is working out why these behaviors happen. Is a fish mourning the dead or are they just stressed because they have new practical considerations, such as finding food on their own? It’s hard to know.
Behavioral Changes After Loss
Clownfish hiding – Photo from Hakai Magazine
Anecdotal reports from fish owners will often suggest that fish mourn their dead. Fish have been observed lingering near the dead, nudging them, or staying in the same part of the tank. This may not be a scientific study, but there are many such reports.
There are common signs of stress in fish. These can happen for many reasons, such as being in low-quality water. When stressed, fish will often be less active, eat less, and will be more likely than usual to hide away.
These behaviors have been studied in the wild. However, fish will often respond to any changes in their environment. It does seem that some fish will have a deeper biological response to loss, but it can’t be ruled out that it is instinctively stressed by a change to its environment.
Do Fish Recognize Death?
To mourn the dead, it first requires recognition of them. Some animals such as elephants and birds have been shown to comprehend the concept of death. Often guarding the deceased or covering them up.
With fish, there is some evidence of this. Cleaner fish which remove parasites from larger fish have been observed avoiding corpses. Guppies have also been shown to react differently when they see dead species members compared to living ones.
This may be a part of their evolution, as there is a survival mechanism here that will help to prevent disease in fish or being vulnerable to predators. It does show that whether through instinct or cognition, fish do recognize when there has been a death and what it means.
Emotional Depth in Fish
Mourning cannot happen without the ability to feel emotions. It was originally thought that fish were primitive creatures that were only driven by instinct. This would mean that all of their actions and behaviors were only a response to their basic needs such as eating or survival.
However, this has long since been disproven. Anyone who has owned an aquarium long enough will be able to tell you this. As mentioned, we know that fish can get stressed and will respond to changes in their environment.
Anecdotally, when you add new fish to a tank, they always appear to be a little hesitant and awkward. After a few days, they are happily swimming around. These changes in behavior can be observed after death as well.
This evidence points towards fish being capable of feeling grief. It’s also worth considering whether or not the feeling of grief is important. As a fish owner, you want to know if your fish are okay.
Whether it is just a biological stress response or a more complex thought, it does seem fish can be emotionally affected by loss. Therefore, it can be concluded they are negatively impacted if one of their tankmates dies, regardless of whether you can technically call it grief or not.
Differences Between Species
It’s also important to reiterate that all fish are different. The likes of cichlids, wrasses, and catfish are social and intelligent species. These types of fish are more likely to have noticeable reactions to changes in their environment.
Fish that rely on group dynamics for their survival also may be more attuned to death. This death, even if it doesn’t invoke grief, can mean they become more anxious and afraid, leading to stress and negative changes in behavior. More solitary fish are less likely to have such behaviors.
Grief isn’t something you can test for with any high degree of accuracy. Some larger fish, such as sharks, are very single-minded so if they were emotionally capable of feeling grief, we couldn’t really ever test that.
Implications for Fish Welfare
If a fish does experience grief, there is very little you can do to help them out. However, it’s also important that their needs continue to be met. For example, if your tetra numbers become too low, they may be more stressed as they should be in groups of six or more.
It’s also important not to presume that fish are grieving. The death could be caused by a change in their environment, such as the water being toxic. This toxic water could then cause behavioral changes in the rest of your fish.
Whenever there is a change of behavior, your tank parameters should be investigated. Ask yourself if all of your fish’s needs are being met. If they are, then it could well be the loss of life that is affecting them.
So, do fish mourn their dead? In reality, it’s a near-impossible question to answer. Fish are more complex than once believed, and changes in behavior after death have been observed. Whether these are complex emotions or purely driven by instinct is unclear, but either way, just make sure your fish are always getting the care they need.
