[leebca]

INTRO
Stress is one of the most often used words when it comes to any general health and care discussion of the ornamental marine fish in our aquariums. What is it? How can we recognize it? Where does it come from? What can we do about it? What are its affects? are all questions we face. It may seem to the novice that it is some kind of joke amongst seasoned aquarist. Sort of like the doctor that can’t figure out what’s wrong with the patient so the doctor says, “It must be a virus.”

But aquarists have come a long way in understanding stress. It's not just an answer to what we aren't sure has happened, or a reason for an unexpected death. Stress in fact is often recognizable and much better understood today than 30 years ago. Using this information and experience is the key to a long lived and healthy captive fish. Can stress be eliminated? We'll see.

I've divided this 'article-post' into seven (7) parts. Intro (this part), Definition, Appearance, Sources, Reducing Stress, Outcomes, Summary, and References.
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DEFINITION
What is it?
It is literally anything (real or imagined by the fish) that causes the fish to be uncomfortable.
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APPEARANCE
What does stress in a fish look like?
From absolutely no appearance to obvious signs of panic. Fishes that show their night-time patterns during the day-time are indicating they are under stress. Signs range from the appearance of 'everything is fine' to tattered fins and a vacant expression. Stress can manifest itself in fish behavior. For instance, a fish that is doing something repetitive (like 'pacing' back and forth in the tank, or constantly picking at the same 'thing' in the tank where there is obviously no food) can be showing signs of stress. Sometimes a chronic (long term stress) shows itself by the fish 'wasting.' The fish thins to death. Quite often it is a fish that has stopped eating, sending a signal to the aquarist that there is stress. The thing about stress is that it can come at the fish being chronic (a slow effect) or acute (a very fast effect). It is the slow effects of stress that are usually ignored or left unnoticed by aquarists. Some of the visual signs (when obvious) are given below with the specific sources. Just remember, just because it isn't obvious, doesn't mean it isn't there and happening.

Probably the best human analogy to what stress in a fish looks like would be people with diabetes. In a room mixed of people with and without diabetes, can you pick out the ones with diabetes? However, do blood tests, urine tests and monitor the person and the diabetics are found. Same with the fish. Stress can be measured in the blood. (See: Stress - A More Technical Discussion)

SOURCES
Where does stress come from?
Anywhere. Some sources are more obvious than others. Stress is generated by any and all of the following and more:
a) capture
b) transportation
c) mental
d) fear/security
e) acclimation
f) space
g) tank mates
h) water quality
I) lighting
j) disease, illness, health issues
k) nutrition deficiency

a) capture and b) transportation - we all recognize these as a source of stress on the fish. Being relocated or displaced against their ‘will’ is no less stressful than it is for humans. Fish suffering from these anxieties often display their night-time patterns during the daytime or even 'play dead' at the bottom of the tank or transfer bag. Not so much nowadays, but much stress was put on fish by the way they were captured. All too well we know the stress caused by cyanide poisoning, and chemicals. Even more stress is being heaped upon fish as global warming changing the reefs and their inhabitants.

c) mental - and after the relocation, some fish just can’t mentally adjust to what they've been through and/or the new captive environment. They may appear to be in a kind of catatonic state, just staring into nothing. They don’t seem to be aware of their surroundings. Have you seen fish like this at your local fish store?

d) fear/security - If the fish gets through the events that brought it to the aquarist’s tank there is still a matter of actually feeling safe. To the fish, this condition is a mix of the fish's perception (mental) and the reality of security. The fish ‘imagines’ it is unsafe or is 'actually' unsafe. This can lead to the fish never losing its fear of captivity, the aquarium, the aquarist and everything going on around them. Hiding is of the greatest importance to them even if they have nothing to legitimately hide from. They often continue to hide until they die.

e) thru I) are lumped into the category of being ‘environmental stresses.’

e) acclimation - of the fish to its new surroundings includes many factors. When aquarists think of acclimation they usually think in terms of acclimating their newly acquired marine fish to their quarantine tank water. Such acclimation to chemical conditions includes the steps taken by the exporter, the wholesaler, and the local fish store (LFS) to acclimate received fishes. Acclimation does include this important first step, but acclimation goes much further. An actual fish acclimation can take days, weeks, or months. Symptoms of an initial bad chemical acclimation to the new water is usually seen within the first 72 hours. It is anything from death to ‘crazy’ behavior, including hiding (as if the fish were afraid), buoyancy problems, etc. After this 72 hour period, if the fish hasn’t had a bad reaction to the new water, the acclimation to captive life, the aquarist, its new surroundings, etc. continues. All the symptoms of a), b), c) and d) can be seen in a fish having long-term acclimation problems.

f) space - is probably the most insidious of all the stress sources. It is the one thing that humans fail to recognize because the fish often doesn’t display any indication of being confined in a space that is too small for it. Tangs and large Angelfish are prime examples. Middle-sized and larger tangs can travel over 25 miles a day in the ocean. If that fish is placed into a short, narrow aquarium, even when it is a 'baby,' that fish becomes space stressed. Another common error made by aquarists is trying to keep one of the large Angelfish (Blueface, Emperor, etc.) in an aquarium under 180 gallons. All large Angelfish that are in transition to adult markings, or which already have adult markings, must be kept in aquariums of no less than 160 gallons. This 'space stress' is totally hidden – most of the time. Some tangs and other fishes will show stress through repetitive actions, like ‘pacing’ the aquarium or picking at the same thing inside the tank, over and over again. Another sign can be aggression towards other fish in the tank. Unfortunately, not all fish will send such a clear message. They will suffer ‘in silence.’ The biggest mistake an aquarist makes here is assuming a 'small fish' is okay in a small tank. If that fish would normally grow large, then when that fish is small, that small fish is always being stressed in a small tank, even if the aquarist thinks the fish 'fits' the tank.

g) tank mates - is one of the more obvious signs of a problem causing stress. But the aquarist must realize that it isn’t only the fish being chased or picked on that is under stress, it is also the fish doing the chasing. The fish doing the chasing feels threatened or challenged and having to constantly chase around an opponent. The chasing fish is under stress too, even if the chaser is dominant. Needless to say the chased fish is stressed! They often hide in the aquascape or seek corners to stay in, especially the top corner of the tank. Don’t only assume that by ‘tank mates’ it has to be a fish! Some fish react poorly to some corals, decorations, rock formations, etc. It isn’t always clear why/how this occurs, but it shows up rarely when something new is put into the aquarium and the fish seems to be visually ‘put out’ or ‘upset’ by the presence of the new thing. This upsetment doesn’t fade but remains strong even after the aquarist thinks it should have gone away when the fish gets used to the addition. Even if the fish seems to accept the new thing, it may be continually stressed by the new addition. Lastly, see how the fish behaves during feeding. Is it afraid to come forward for food? What is your community tank's pecking order? Is the bottom of that order getting its nourishment? Look for signs of bad interactions between fishes, especially at feeding times.

h) water quality - is very important to marine fishes. Their skin comes in contact with the water. Some water passes through their skin and carries with it a variety of trace elements. But more importantly, the fish is drinking water constantly. When the water goes bad a fish will usually let you know IF you are looking for subtle signals. Since some aquarists don’t focus on the details of their fishes that much, the best general thing to do is do regular water analyses. If the fish stops eating, there is something going wrong. It could be water quality. If the fish changes its normal behavior, check the water quality. A change in respiration rate could mean gas exchange is not going well.

I) lighting - is often overlooked when it comes to fishes. Like reefkeepers struggle with the proper lighting for their corals and invertebrates, they often forget what it means to the fish. A simple sign of light problems includes the fish hiding in dark places in the tank or even up high in the corner. A step up from this sign is actual damage to their skin. The extreme signal is a fish that has gone blind from too much light.

j) disease, illness, and health - are all recognized as being a great source of stress on captive marine fishes. The aquarist often doesn’t appreciate that in the wild, the fish can ‘escape’ getting heavily infected by parasites because it moves around. In the confines of the aquarium, where the fish can’t get away, the parasites can rule. From the parasite’s point of view, they have a captive food supply! What some aquarists fail to realize is that if they let disease in their tanks and even if their fish seem to ‘survive the plague’ it causes a great deal of stress to the fish. Those who don’t keep Marine Ich (Cryptocaryon irritans) and/or Marine Velvet (Amyloodinium ocellatum) out of their display keep these organisms alive and draining the health of the fish, causing an ongoing, chronic stress.

k) nutrition deficiency - is another stress source that the aquarist doesn’t see. The aquarist typically says, “My fish eats well” or “My fish is fat” or “My fish eats like a pig” but doesn’t realize that these ‘signs’ don’t mean the fish is getting the nutrition it needs. In fact some of these signs (My fish eats like a pig) could be a symptom of the fact that the fish is ‘starving’ for some nutrient the aquarist is not supplying.
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REDUCING STRESS
What can we do about relieving stress?
From the above mentioned sources of stress, it is obvious some of the things that can be done and not done to reduce stress on the fishes. Some things are in the aquarist’s control, others aren’t.

a) capture - is pretty much out of the aquarist’s control. But the aquarist should use the greatest power they have over the system – their money! Don’t buy fish that has any symptom of handling/transportation stress. Don't buy fish that weren't captured properly (hard to do, I know). Don’t buy fish with any kind of injury, illness or malady (you are not a fish hospital nor veterinarian). If the aquarist tries to 'save' sick or injured fish they don't own they are only encouraging mis-management of those fish in the hobby system. Even if the fish was fine, if the owner nets the fish and drops it on the floor, squeezes it between net and aquarium wall, or in any way may have harmed the fish, refuse to buy it. Don’t buy any fish that isn’t eating. Don’t buy any fish that you think wasn’t or might not have been properly acclimated through the system. Ask around of other aquarists to see what success they’ve had acquiring fishes from the source you want to acquire them. Very importantly. . .Ask how long the fish live that come from a particular source. The answer gets complicated and not always reliable because many LFSs obtain their fishes from different wholesalers who obtain their fishes from multiple exporters who obtain them from multiple collectors. Still, it is worth getting a feel for the longevity of fishes coming from any particular LFS.

b) transportation - whether from the LFS to your home or if you choose to purchase fish on-line and have it delivered, the same applies to the aquarist as it does the exporter, wholesaler, and LFS. The least stressful trip is one where the temperature is held constant; the light remains constant (preferably dark or at least not in direct sunlight); and the container has not only enough water, but enough air/oxygen above the water. The best ratio I have found is that for every one part of water in the bag, there should be two parts of air/oxygen if the fish will be in the bag for more than 4 hours. Otherwise, 50/50 is good. The aquarist can’t usually tell the source how to ship if they are on the Internet, but again, the aquarist should use their power – money. The Internet shipper is usually only concerned about getting the bag(s) into a single box.

c) mental - is pretty much the most difficult for the aquarist to control. If the fish is ‘mental’ what can you do? The best the aquarist can do is make the fish as comfortable as possible and hope they ‘come out of it.’ This means providing the hiding spaces and security that particular fish is used to having. Using a quarantine process helps these fish out tremendously. Beyond this, it is just having the best water quality as possible.

d) fear/security - is best addressed by providing hiding spaces. It is especially a good idea to utilize a quarantine procedure to provide security. The newly acquired fish doesn’t have to put up with other fishes or neighbors. Controlling other stress factors (e.g., lighting) can improve the fish’s sense of security. People moving around the tank is another source of fear. Sometimes the aquarist forgets the size difference between their fish and humans. If you turned around and saw King Kong standing in front of you staring at you how would that make you feel? Have to clean out your shorts? Well, it is no less for the new fish who has found, in general, association with these huge creatures (humans) to be painful and very stressful up to this point.

e) acclimation - is a key point of the fish’s captive existence. There is no formula for absolute success that is easy. The aquarist is bombarded by a dozen different acclimation procedures and techniques. The fact is, the water quality the fish is in, must match the water quality of the fish’s next tank. Either the bag water has to be adjusted, or the quarantine tank water has to be adjusted to the bag water. Although the aquarist can follow drip and water additions to bag water, based upon time and volume, the only absolute way of making sure the fish water has been adjusted to the tank water is to measure the pH, temperature, and salinity (specific gravity) and see that, after all is said and done, the water in the bag matches the water the fish is about to enter. That adjustment must occur over an appropriate amount of time (suitable to the species). Even when the 'chemical' acclimation is finished, there may still likely be the acclimation to captive life which can take days, weeks, or months after the fish is put into the aquarium. Ideally the fish was first put into a quarantine tank so that the fish can get used to the human, the foods, and the new conditions before it finds its way into the display aquarium. The quarantine process makes acclimation to captive life MUCH easier on the fish. The long term acclimation process can best occur when the fish is in quiet conditions and in a state of well being. (That is, if the fish thinks it’s okay, it will be okay – and the reverse).

f) space - the final frontier? The stress of a fish not having enough space goes unnoticed for the most part. Some fish send vague signals that they are short on space (pacing and, aggressive behavior), or sometimes the fish will spend a lot of time facing into a powerhead to have the water flowing over them while they swim 'into the current,' others do nothing. The best the aquarist can do is not put fish in aquariums that are unsuitable to them. Tangs do belong in long aquariums (6 or more feet) when they are of almost any size. Large Angelfish transitioning to their adult pattern or which have already achieved their adult pattern, must be in aquariums no less than 180 gallons. Paired fish need more space than each would if they were single, so the aquarist must account for this added space. Some fish take tank bottom space (gobies) so the allocation of bottom area is what is important to them, not the number of gallons in the aquarium. Fish travel horizontally, not up or down, so the height of the aquarium isn’t as important as its length and width. If you want to keep tangs and rabbitfishes (or any fish that travels a lot in the open ocean or seas), put them in long aquariums. Don't put fish like this in small aquariums, even if the fish is small now, thinking it will be okay for now. They are not okay. Baby fish that become large need their full space right now.

g) tank mates - is not just a matter of planning. Planning is important, but fishes differ even within species. This one (you'd think) is easy for the aquarist to control. Unfortunately, purchasing a fish at the LFS can be a spontaneous act -- like grocery shopping when you're hungry. It is best to have a plan of what you want in the aquarium and try to stick to it. If the compatibility of fishes on your wish list are unknown, get to a forum or friends and start asking around. I would definitely NOT recommend taking the advice of your LFS on this. Not that they are all wrong, don’t know, or lie (most do one or the other(s) in my experience) it’s just that they have a limited experience based upon crowded store tanks that don't reflect your community tank. The LFS is there to sell product and to them, fishes are products. They make more money if you buy the wrong fish and then you have to buy medicine to fix the injured fish, or you have to replace the fish that died. Starting off correctly is the best way to avoid this stress. If even you planned carefully, a particular fish can be 'out of character' either aggressive or submissive. When two fish are not getting along after a few days, it’s time for one or both to go. The same goes for the introduction of any new thing to the aquarium. If the fish doesn’t like it or get used to it in a few days, it’s time to take one or the other or both out. Remember, when two fish don’t get along they are both under stress – the one chasing and the one being chased. Another subtlety is watching your fishes during feeding time. Are any afraid to come to the feeding area? There are subtle signs of stress between fishes that often come out during feeding time. Watch closely and remove the aggressor or the recluse or both.

h) water quality - is a big matter for fish. The emphasis is to provide excellent water quality for corals and invertebrates, but fish benefit immensely from this, even if they are the ‘tougher fish.’ The fish drinks water and separates out the salt so that it can ‘take a drink’ of freshwater. The fish maintains its internal salt content through a process referred to as osmoregulation. This takes energy and if there is anything amiss with the water, then stress is added to the fish. Everything: temperature, salinity, ammonia, nitrites, pH, organics, etc. has a varying degree of impact on the fish depending upon not only what that species can tolerate, but what that one particular fish can tolerate. One of the most overlooked water quality issue is the pH. Focus by the reefkeepers is to strictly control pH, for their invertebrates and corals, but pH is just as important to marine fishes as it is to the invertebrates and corals. Not all fish like the same pH. Tangs especially like a pH of 8.4. Many angelfishes like 8.3 to 8.4 pH. Large Angelfish in particular are found by new aquarists difficult to keep alive for more than a year. Some reasons include space stressors (see above) and one of the other is pH and water quality control. Large Angelfishes need the best water and a steady pH in their preferred zone to live long and healthy lives. Large adults angelfish I've maintained have lived over 10 years in captivity and still going. As long as I've seen them live, I've seen them 'check out' quickly in tanks that aren't mature, water quality isn't maintain, or pH fluctuates. Mature tank? See: The Mature Aquarium. The best control the aquarist has in this area is to know what water quality issues are significant to the fish and then provide it!

I) lighting - like for corals and invertebrates, is a matter of choosing the right ones suitable for the fish. Since the fish’s survival isn’t strongly linked to light, it's easy to choose the wrong bulb (a bulb high in UV content) for a fish. If the fish was collected from deep waters, then the fish isn’t used to bright lights. The fish must be given places to hide in the near dark, or not put into such an aquarium. Aquascaping to provide overhangs, holes and dark places will be important features for fishes coming from deeper water. Even fishes that supposedly come to us from the ‘coral reefs’ may in fact have been collected from deeper waters. So unexpectedly to the aquarist, the fish they have needs darkness and shelter from the lights, but their friend’s same species of fish is fine being in the bright light. Watch for subtle signals and adjust the light intensity, composition, and aquascaping.

j) disease, illness, health issues - are all sources of stress. The best the aquarist can do is quarantine all newly acquired fish before they can bring a problem to the display tank. The next best thing an aquarist can do is keep disease out of the display tank. Each fish should be kept in quarantine. Don’t take refuge in one liners like, “The fish looked healthy at the store.” Acquiring a new fish is an emotional event for most people. The aquarist doesn’t always see the flaws AND not all flaws are that readily apparent. Until you’ve examined their gills, intestinal track, kidney and liver, you don’t know if they are healthy or not. Forget the dodge. Do the quarantine. Quarantine provides other reduced stress environments too (see above).

k) nutrition deficiency - is something to avoid! Aquarists don’t realize that they must provide their fishes with vitamins, fats, and trace elements besides the foods they usually feed. It is my opinion that no store bought food contains these three nutrients in the proper quantity and in a complete formula. Follow the guidelines in the reference below.
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OUTCOMES
What are the affects of stress on fish?
Probably the most outstanding of all final outcome is a shortened and less healthy life. This is hard for the aquarist to appreciate and accept. They think their fish is fine and the fishes will live a very long time. Well, the fishes should live a long time. When they die in a year or even 5 years, the aquarist wonders why? Stress got to the fish. A stress the aquarist refused to acknowledge (most often something like needing more space, and/or not getting the right nutrition) or a stress the aquarist didn’t see/watch (water quality drifting from reduced maintenance over time).

One outcome of stress is the fish succumbing to diseases and infections (mostly bacterial in nature) whereas an unstressed fish would be okay. Quite often, this is one fish in the tank and not all the fish and the aquarist comes to the wrong conclusion, that nothing's wrong with the water, environment, tank-mates, etc. The aquarist thinks everything is fine then their fish gets one cloudy eye, then two, or develops Popeye, or has tattered fins when no other fish has been bothering it. The decline of the fish, either slowly or suddenly is the product of stress.

The definitive outcome of stress is an untimely death. Misunderstood and often going unacknowledged, stress is a killer. Often is asked the question, “Why did my fish die after xx months or y years?” when the real question is “Where was stress coming from that cut my pet’s life short?”
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SUMMARY

It’s a challenging hobby. There are many aspects to the hobby that make or break our success. Every tank is unique in its own way and that makes broad sweeping absolute statements impossible. But I hope the above has provided at least some things deserving your attention.

Something goes wrong in the tank (e.g., water quality). The aquarist, after an amount of time, sees/notices what is wrong and fixes it. Everything is fine, right? NOT! During the time things were out of wack, the fish was under stress. It lost some of it longevity that the 'fix' will never give back. Stresses accumulate and can't be 'undone.' We have only the opportunity to understand and prevent stresses.

It's good to remember that in general, marine fish are always growing. They never stop growing. Although your captive fish may not reach its maximum size, it is nonetheless growing. When the fish stops growing or shows no sign of growth, something is wrong and that wrong can be traced to one or more of the above mentioned stress sources.

Back to the original question in the Intro. Can stress be eliminated? Probably not. But we can get real close to it as evidenced by fish living a healthy 20+ years in captivity.

Thanks for reading this. [Ending with the song Under Pressure by Queen].
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REFERENCES
I’ll refer the reader to this post when I see where a fish/pet of theirs may be under stress.


Some useful references and additional reading:

Quarantine tank and system:
http://reefkeeping.com/issues/2004-1...ture/index.htm

Fish feeding and Nutrition:
Feeding Marine Fish and Fish Nutrition

Stocking the fish medicine chest:
Stocking the Marine Fish Medicine Cabinet

A dip procedure for newly acquired fishes:
Freshwater Dip for Marine Fishes

Copper as a stress source:
Copper - Treatment, Use, Problems

Want some technical information about fish stress? Stress and a clinical approach:
Stress - A More Technical Discussion

Tap water as the wrong source for making saltwater:
http://www.advancedaquarist.com/issues/jan2004/chem.htm

[Poseidon]

BRAVO! Excellent Post Lee!

[anthias]

realy very useful thread,thanks leebca

[leebca]

Thank you Poseidon and anthias. More could be added, but I thought it was already too long!