Depression in Fish

[Stigigemla]

In Austria there is a fish behavour scientist, Ellen Thaler that has been working with fishes in more than 25 years.
She has written a book, Fische beobachten that has a lot of content per page.
In English the title would be: Looking at fishes.
I recommend it very much for eveeryone thats reading german.

 

[GoldeneyeRet]

Perhaps our fish lead unfulfilled lives? I see petco now offers canine weddding planners, maybe they could branch out into fish weddings and we can give our finned friends the ceremony they long for.

I'm with ca1ore,this is purely anthropomorphism.

 

[Dr. Dendrostein]

Seawitch submitted a new Article:

Depression in Fish

The photos included in this article are not depicting depressed fish, but rather they are just some good fish photos from the Reef2Reef archives showing different species that we commonly see in saltwater tanks. ©2019, All Rights Reserved.

We often set up aquariums for the joy that they bring us, the soothing feelings we get watching colorful fish flit around beautiful coral displays and the deep satisfaction the aquarist gets from having built and cultivated something impressive. With all the happiness that can be created by an aquarium have your thoughts ever drifted to the emotions of the little finny friends that occupy that gorgeous tank?

Powder blue tang photo by @ChristopherKriens.

While fish are not often thought of as very emotive animals they are actually quite emotionally complex possessing very similar neurochemistry to humans and are often used in trials for psychiatric drugs. This means that yes, fish can get depressed just like their owners. But how do you recognize depression in fish and what can a concerned aquarist do about it?

As fish cannot sit down with a therapist and discuss their concerns and worries we can identify depression in fish by observing their behaviour. One of the most notable indicators which should be easy for most aquarists to identify is the degree to which a fish explores his or her tank. Depressed fish tend to linger in one spot, usually near the bottom and will rarely move around the entire tank. The key element here is inactivity as depressed fish will just let the currents of the water move them around, allowing themselves to sink to the bottom and not swimming to the top for mealtimes.

Starry blenny photos by @MJC.

There are some fish species that stay in one small territory as part of their normal behavior. That's not what we're talking about here. We're talking about the fish that would and should normally swim around but chooses not to.

One test that aquarists can perform in order to see if their fish is depressed is to introduce it to some new surroundings, as most fish are naturally curious they will, when in a healthy state of mind, immediately begin to explore the new environment or feature whereas a depressed fish will often allow itself to sink to the bottom and remain there.

Royal gramma photo by @Joey Bekius.

What causes a fish to become depressed? According to Victoria Braithwaite, a professor of Biology and Penn State University, some of the most likely causes are a lack of stimulation or insufficient oxygen in the water. Another cause can be chronic stress, which can come from and be enhanced by a variety of sources.

Some of the most common stressors to occur in an aquarium environment include overcrowding, inability to avoid aggressive fish, a struggle for food and changes in lighting and currents. Thankfully, unlike humans, genetic causes of depression are rare in fish, usually only occurring in selectively bred fish used for laboratory research so you shouldn’t need to worry about having to flood your tank with Prozac or put your fish on medication to deal with their depression.

In situations where you aren’t dealing with a genetic mutation that requires chemical correction of the issue there are steps an aquarist can take to improve the livelihood of your fish and mitigate the effects of stress and depression. As fish can become bored with their surroundings one of the simpler solutions to ichthyoid depression involves enriching their environment, doing things like adding some new marine flora or some interesting decorations and ensuring that more nervous fish have plenty of places to hide and plenty of room to get some safe space. It might also be prudent to check your filtration system to ensure water quality.

Purplelined wrasse photo by @Acorral
​

Remember that the warmer your water is, and the saltier it is, the lower the oxygen saturation. The solubility of oxygen decreases as temperature increases, and dissolved oxygen decreases exponentially as salt levels increase. (1)

For increasing oxygen in the tank, sometimes something as simple as opening a window in the room where the tank is helps the oxygen uptake in the water. More surface agitation will help with gas exchange, and that's easy to accomplish with changing the direction of a powerhead or adding another one or adding a small air pump and bubbler or adding a skimmer.

You could also observe your depressed fish and determine if it is being harassed by any other fish and take steps to separate them or give them space apart from each other. Another simple solution is making sure that when feeding your fish you spread the food around, reducing competition for food among tank denizens. In extreme cases where your fish are being crowded your options are a lot more limited: get a bigger tank, get a new tank, or get rid of some fish.

Harlequin tusk fish photo by @OrionN
​

We recognize that discussing the emotional lives of your fish is a new concept and one that will likely bring about some debate and disbelief. However, the fact that fish are intelligent and have emotional lives is what the recent peer-reviewed research is concluding, so as aquarists, it's something we need to be aware of. In humans, untreated depression shortens life expectancy, so it's not a big step to suggest that untreated depression may shorten life expectancy in other species as well.

It probably doesn’t come as a surprise to experienced aquarists that fish are more emotionally complex than many people give them credit for. Fish have been observed exhibiting complex emotions such as joy, relaxation and playfulness and as we’ve already noted, depression and stress. Hopefully with our discussion above we’ve given you some solid strategies to minimize the stressful and depressing elements in your fish's lives and to bring out the best emotions in them, so you and your fish can both enjoy each others company to the fullest.

* * *

Sources

· (1) Fondriest Environmental, Inc. “Dissolved Oxygen.” Fundamentals of Environmental Measurements. 19 Nov. 2013. Web. < https://www.fondriest.com/environmental-measurements/parameters/water-quality/dissolved-oxygen/ >.

· https://www.huffingtonpost.ca/2013/08/09/depressed-fish-study-new-drug-treatments_n_3714691.html

· https://www.jhunewsletter.com/article/2017/11/research-shows-that-fish-can-also-get-depressed

· https://www.sciencedaily.com/releases/2010/11/101116101736.html

· https://www.the-scientist.com/news-...ressants-span-three-generations-in-fish-65193

· https://www.animalsaustralia.org/features/fish-in-farms-are-depressed.php

· https://www.hartz.com/en-ca/stress-in-fish-symptoms-and-solutions/

· https://www.upi.com/Science_News/20...-salmon-suffer-from-depression/5391464194628/

· https://www.fetchpetcare.com/blog/facts-fish-depression/

· https://www.animalsaustralia.org/features/fish-facts.php


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Author Profile: Peter Steckley

Peter Steckley is a freelance science writer based in Calgary, Alberta, Canada. When he's not studying reef aquariums or testing out new recipes on his family, he's usually reading or enjoying the latest video game releases.

Thank you for article, of all fish a certain tusk fish has an intelligence very few fish can surpass. This fish goes out of the reef moves coral rubble around to a find one certain type clam picks it up and goes back to the reef to a special Coral that has a hard surface in the center and cracks open the clam and eats it. The creation is awesome

 

[Dr. Dendrostein]

Perhaps our fish lead unfulfilled lives? I see petco now offers canine weddding planners, maybe they could branch out into fish weddings and we can give our finned friends the ceremony they long for.

I'm with ca1ore,this is purely anthropomorphism.

Maybe a dating website for our fish, similar to plentyoffish.com

 

[Fourstars]

If I were to date a fish it would be my marine betta. She is such a tease.

 

[Dr. Dendrostein]

Might as well...maybe she won’t be as mad at your hand with a little hubby to push around [emoji23][emoji23]

Yeah, she'll have him whipped in no time.

 

[Dr. Dendrostein]

Might as well...maybe she won’t be as mad at your hand with a little hubby to push around [emoji23][emoji23]

Before you know it you'll be getting up turning on the fan for her, making her a sandwich, she would tell her mom how he makes her sandwiches and the mom would say she would mention it to her father, but he's making her a sandwich to. Whipped I tell you

 

[mtfish]

I think all fish become depressed when taken from the ocean and put in glass jails. Seriously, until someone can close the gap and actually talk to a fish, all these types studies are silly. We have a hard enough time explaining what depression is in people (who we can talk to). Observing a behavior is one thing, but stating the cause is depression is a leap of faith. Believe if you want, but it does not mean it is true.

 

[4FordFamily]

Depressed VS Stressed:

Personally, I hesitate to consider fish "depressed", I am more inclined to call it a "stressed" animal. Many organisms show stress. Stress can and does kill, and it should still be remedied.

To me, depression is a condition found in highly intelligent animals whereby an immediate change in environment or circumstances "causing" said feelings may or may not solve the issue. I.E. someone cannot control their feelings anymore, and it is beyond rational reason to an outside observer -- it's a condition that requires thorough treatment and is quite complex and difficult to understand. The feelings are real but the stimuli are further removed on occasion. Very perplexing and frustrating to handle, but more intelligent creatures suffer from complex social/emotional conditions such as this.

Inversely, a stressed person or organism, in contrast will return to normal behavior almost immediately upon the stressful conditions being remedied. This unless the stress has caused health issues -- but in this case if the health issues are remedied I'd argue the organism would likely immediately behave as normal as well, as poor health is a stressor.

Admittedly, some fish such as puffers, for example - exhibit some very complex thoughts and problem-solving skills. They recognize and "like" some people more than others, they can learn to "play games" and even solve problems. I saw somewhere some videos of wild pufferfish doing math or something equally as impressive, but I cannot find it now. They seem to need to carry things around both to sharpen their beaks functionally but even for "fun". Some tuskfish can use tools, and I highly suspect that fish are more "intelligent" than we think. Lionfish for example strike me as a very "stupid" animal. There is no reason for them to be intelligent, they need only to sit camouflaged and wait for prey and then gulp them, and repeat. I'd say lionfish or many similar ambush predators and small schooling fish are probably at the low end of fish intelligence spectrum and actively hunting predators or fish that need to avoid predators frequently based on their geography or feed on a food source that is difficult to find/extract are likely towards the high end of the fish intelligence spectrum.

That said, intelligence in humans and fish intelligence are two very different things. We've evolved a need for advanced problem-solving, emotional development, social development, and "change intelligence" in order to survive. Since we aren't notably fast, large, or strong we evolved an impressive brain to solve these problems to make us adaptable when we weren't otherwise based on physical features. Relative to the size of the normal fish brain, I'd say we should be quite impressed with their intelligence and capabilities. I also don't think we've even scratched the surface of a true understanding of fish intelligence. I imagine there is more there than we understand. If comparing fish to other animals, I'd hesitate to call them "smart". Perhaps smarter than we thought, but that depends on our benchmark.

**This is just my own opinion, I don't have any scientific support for it. I'm not a scientist, nor a marine biologist. I understand and study human psychology but I am not a true expert in this subject matter, either**

@evolved @eatbreakfast I am interested in your viewpoints, as you two are quite adept with regards to fish behavior, in my opinion.

 

[Mariette]

great article!

 

[4FordFamily]

Stressed …. yes; depressed …. not so sure. Anthropomorphism at work perhaps . Added a gam tang to my tank with a resident purple. Latter beat up the former which hid and would not eat. Removed latter and former came out and within a day was eating and swimming normally. Reintroduced the latter after 6 weeks and former beat up latter which would hide and not eat. Stress ….. not depression. I don't think I have ever seen a fish that didn't recover from a stress event when the stress vector was removed. I'm not buyin' it.

I more or less agree with this and missed it when I posted my view above.

I am not saying depression is impossible in fish, rather it's much more likely that stress is the issue. I am not an expert in the subject matter, but I do know of a human's underlying tendency/bias in anthropomorphism. I also think the term "depressed" is incorrectly used by many humans, as well. Perhaps the issue lies there in the definition of depression. I'd argue in humans, if the removal of the stressor/stimuli immediately remedies their behavior/feelings, then you're actually dealing with stress as well. We humans have a tendency to be quite dramatic. Depression is very different from being sad or very stressed, even if it happens frequently. Eventually, this can lead to true depression, however. We're immensely complex organisms in this regard.

Again, just my unsupported .02!

 

[eatbreakfast]

Looking at the references it appeared that the "depression-like" symptoms were related to chronic stressors. In the examples with the zebrafish and aquacultured fish they were noticing the changed behavior due to the high stress conditions of overcrowding, and unwanted social interactions. And it was measured bt cortisol production, aka the stress hormone. If they are removed from the stressor normal behavior eventually returned.

 

[4FordFamily]

Looking at the references it appeared that the "depression-like" symptoms were related to chronic stressors. In the examples with the zebrafish and aquacultured fish they were noticing the changed behavior due to the high stress conditions of overcrowding, and unwanted social interactions. And it was measured bt cortisol production, aka the stress hormone. If they are removed from the stressor normal behavior eventually returned.

So then if my perhaps unscientific comparison above has any merit, this too would imply stress over depression.

 

[Seawitch]

I think I'll try to contact some of the scientists doing the research and do a follow-up piece. I'm actually surprised at all the push-back, but I'm a bit naive. It's a big paradigm shift for everyone to go from "fish are stupid" to "fish have complex emotional lives."

 

[4FordFamily]

I think I'll try to contact some of the scientists doing the research and do a follow-up piece. I'm actually surprised at all the push-back, but I'm a bit naive. It's a big paradigm shift for everyone to go from "fish are stupid" to "fish have complex emotional lives."

I am no scientist, and I definitely submit to the idea that many fish are more intelligent than we’ve habitually given them credit for.

Certainly not intending to push back, just sharing my viewpoint. As I said, I’m no marine biologist and I am solely drawing on my observations of fish behavior throughout my life. I’ve observed them diligently and solved some fish behavior problems using these observations but that’s not a doctorate in marine biology. I’d love to hear/see their response to my viewpoint.

And within the scientific community I imagine there is plenty of dissent on such a topic.

Perhaps it’s the use of the term “depression”. I’m thinking of it as clinical depression and I think it’s more commonly used in society to describe sad behavior or feelings over some period of time to varying degrees (stress).

 

[eatbreakfast]

I think I'll try to contact some of the scientists doing the research and do a follow-up piece. I'm actually surprised at all the push-back, but I'm a bit naive. It's a big paradigm shift for everyone to go from "fish are stupid" to "fish have complex emotional lives."

Just reading the article one quoted rearcher said this:
"According to Victoria Braithwaite, a professor of Biology and Penn State University, some of the most likely causes are a lack of stimulation or insufficient oxygen in the water. Another cause can be chronic stress, which can come from and be enhanced by a variety of sources."

And the article gives an example of low O2. Now the behavior is lethargy, not depression with low O2. Compare that with humans. If someone is lethargic because of low O2 a doctor doesn't diagnose and treat for depression. And for the fish increasing O2 eliminates the symptoms.

Another situation provided in the article is to see for bullying. But again, once the bully is removed, the victim's behavior goes back to normal.

In farmed salmon they are kept in a significantly higher density than aquarium fish and in many cases are given antidepressant medications, but this done in effort to control cortisol levels, as cortisol acts as a growth inhibitor. The goal for farmed fish food is to get them as big as possible, as fast as possible, and medicating seems to be the moat cost and labor effective solutions to dealing with cortisol.

In most casss I've witnessed in aquaria what can be described as "depression-like" symptoms can attributed more to lethargy than depression. Obese fish become lethargic, but fixing diet solves that. Parasites and disease can cause similar symptoms, and treating the fish for the disease or parasite is the solution. Bullying and low O2 also have easy fixes that bring results.

 

[ca1ore]

I'm actually surprised at all the push-back.

I think it is fun to debate these things - as long as it is done constructively and respectfully (which I always strive for). Lots of things that appear prima facie to be absurd end up being true; and lots of things that appear intuitively obvious end up false. I tend to be a skeptic and often take a devil's advocate approach to things just to see if folks can mount a cogent argument. The more opinions coalesce around a particular point of view, the more likely I am to think its wrong . Oh man, now I feel sorry for my kids …….

 

[Seawitch]

I think it is fun to debate these things - as long as it is done constructively and respectfully (which I always strive for). Lots of things that appear prima facie to be absurd end up being true; and lots of things that appear intuitively obvious end up false. I tend to be a skeptic and often take a devil's advocate approach to things just to see if folks can mount a cogent argument. The more opinions coalesce around a particular point of view, the more likely I am to think its wrong . Oh man, now I feel sorry for my kids …….

I'm reminded of a quote by the English philosopher and mathematician, Bertrand Russell, “Even if all the experts agree, they may well be mistaken.”

 

[Webslinger]

Add a few drops of THC to the water....Their depression should subside.

 

[Dr. Dendrostein]

Add a few drops of THC to the water....Their depression should subside.

First you got to figure out what kind of depression they have then you know which type of medicine to pursue for fish, poor fish, you're going to kill it that way not knowing what type of depression they have first. Heehee

 

[Neo Jeo]

I add a little Ativan in my fish food. Problems solved