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Causes Of Stress To Aquarium Fish

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This is from an article that I've read and thought I would pass it along...good reading for everyone! I think it's very important to minimize stress wherever possible ;)

-Dennis

In all cases, the level of stress induced by a specific

factor is highly species-dependent. You should be aware of the type of

stress that will be present in your tanks and select fish known to

tolerate such conditions well. For example, if your water is hard and

alkaline, you're best off selecting fish that thrive under such

conditions.

Nitrogen compounds (ammonia, nitrite and nitrate) have varying degrees

of toxicity and are stressful at all levels. Ammonia is toxic in low

concentrations and severely stresses fish under ANY concentration.

Consequently, a healthy aquarium must have an adequate biological

filter that quickly converts ammonia to nitrite (and nitrate).

Although significantly less toxic than ammonia or nitrite, nitrate

also stresses fish. Thus, a means of removing excess nitrate (e.g.,

through regular water changes) helps keep an aquarium healthy.

The water temperature of your tank should match the needs of its

inhabitants. Keeping water temperature too cold or too warm for a

particular species will stress those fish. For example, goldfish

prefer cooler temperatures than most tropical fish

(goldfish survive winters in ponds where temperatures approach

freezing), guaranteeing that a tank containing both goldfish and

tropicals will either be too cold or too warm for some of the

inhabitants.

Some fish prefer soft water, others prefer hard water. Keeping a

soft-water preferring fish in harder water (and vice versa) is

stressful.

Some fish prefer acidic water, some prefer alkaline water, others

prefer water with a neutral pH. (Some fish don't care too much.)

Some fish live in brackish water conditions; they will do better in

water with a small amount of added salt. Other species are extremely

intolerant of salt. Add salt only if all of a tank's inhabitants can

tolerate salinity. Mollies, for example are known to like salt,

whereas many species of catfish tolerate no salt at all. In general,

fish lacking scales (or having small scales) don't tolerate salt well.

The amount of physical space required for a particular fish depends on

its species. Some fish do just fine in a 10g tank, others need 100g or

more. Keeping a fish in a tank that is too small for it increases the

level of stress (on everyone), frequently leading to increased

aggression among tank inhabitants. Note also that the amount of space

required may change should fish pair off to breed. Cichlids, for

example, claim a portion of the tank for themselves when in breeding

form, chasing away any fish that encroach on their territory. Thus,

the onset of breeding behaviors frequently increases stress levels.

Not all species of fish mix well with others. As an obvious example,

most cichlids will eat smaller tank inhabitants (e.g., anything they

can fit in their mouths). Even if too big to be eaten, however,

peaceful fish will be stressed if kept with aggressive fish that chase

them around all day. Moreover, many fish communicate through behavior

and body language (i.e., cichlids frequently establish a ``pecking

order'' in which one fish is king). Fish of one type of species may

not recognize the signals given off by others, guaranteeing continual

strife.

Some fish school in nature, spending their entire lives in large

groups (rather than individually); they never feel comfortable or

``safe'' when kept by themselves. Cory cats for example, do better in

a tank with 6 or more other Corys than they do by themselves. While it

may be tempting to buy six different kinds of fish, this may not be

ideal for the fish themselves. The opposite can also be true. Some

fish are more aggressive towards members of their own species (e.g.,

mating behaviors), whereas they may not feel threatened by other

species and pretty much ignore them.

Fish need oxygen, and some fish are more tolerant of low-oxygen water

than others. Water with insufficient oxygen stresses fish. Note that

as the water temperature goes up, the amount of dissolved oxygen in

water decreases.

Poor nutrition also causes stress. A healthy diet is a varied diet,

and one should avoid using old foods in which vitamins and other

nutrients have broken down. ``Old food'' includes food that has been

stored in hot places, been exposed to air (not sealed), etc.

The ``cure'' of adding medicines to tanks is often worse than the

original disease. Medications that kill bacteria, parasites, etc. are

usually not too discerning: they may also kill your nitrifying

bacteria (now you REALLY have a major problem) or be toxic to the fish

themselves. For example, some species of fish do not tolerate certain

types of medicines at all. Adding such medications may weaken healthy

fish to the point that they become susceptible to the original

disease.

Adding untreated water to your tank may introduce chlorine or

chloramine, both of which are toxic to fish. Be sure to treat all

water prior to adding it to your tank.

Sudden changes in water conditions can be stressful. Within limits,

most fish can adjust to sub-optimal water conditions (e.g., wrong

temperature, wrong pH). However, fish have difficulty adjusting to a

SUDDEN change in water chemistry. Thus suddenly raising (or lowering)

the temperature, changing the pH, changing the water hardness, etc.

stresses a fish. It is more important to keep the water chemistry

stable over the long haul than to keep keep water conditions exactly

optimal.

In summary, many factors lead to fish stress. Minimizing and

eliminating sources of stress increases the chances of keeping tank

inhabitants healthy. The exact amount of stress an individual fish can

take depends greatly on what species it is, its age and size, etc. A

stressed fish is a weakened fish. Although it may appear healthy to

the casual observer, it will be more susceptible to disease, injury,

etc. In contrast, healthy (unstressed) fish will be able to ward off

disease and infection on their own. Thus, the appearance of disease in

a tank is frequently brought on by ``poor water conditions'' that

leave fish with weakened immune systems.

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That is an excellent article. And one we should all really take to heart and listen to. It is a proven fact that avoiding stress factors is the key to good health in fish and to long life. Stress in fish is a very different thing from human stress which can be controlled and managed with various emotional and mental support tactics. These are just not available with fish and their tiny brains and limited lifestyles :)

Here's an article I wrote I'd like to share, if I may too:

http://www.kokosgold...ressInFish.html

Thanks Dennis for bringing this important topic to attention.

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Thanks Imo...

Thought I'd put yours in here too...tons of info on stress.

-Dennis ;)

STRESS IN FISH

Something often overlooked and definitely under researched is the effect of stress on goldfish. We often hear that a disease may have been triggered by stress but how is that and why is that? And how can we create a stress free environment for our fish pets? I have tried to find as many answers and gather as much information as possible about stress in goldfish and will set it out here as simply as I can in 3 question and answer parts.

1.What is stress and why does it affect the fish negatively?

Stress is the reaction of a part of the brain called the hypothalamus to a stressor. The hypothalamus re-acts to the stressor by beginning a chain of chemical activity that results in the production of hormones from the adrenenal glands. In people these are located around the kidneys and in goldfish due to their small compact bodies the glands are merely adrenenal tissue inside the kidneys.

When the fish encounters a stressor (more on stressors below), the adrenenal tissue produces 2 hormones. The first is epinephrine. This is the hormone that prepares the fish for adversity. It sends blood flowing faster to the brain allowing for the uptake of more oxygen, it speeds up the heart, it utilises nutrition to provide extra energy to combat immediate threat.

This is all good. But only short term. If the hormone continues to circulate (in conditions of enduring stress) it weakens and exhausts the fish dramatically.

The second hormone that is produced is cortisol. This is a powerful hormone that increases metabolism. It is also dangerous to the immune system of a fish when prolonged. It disturbs and damages the protective immunity process called phagocytosis.

2.What is phagocytosis?

This is the name given to the complex process of cell invasion and neutralisation. When a bad bacteria settles on the fish, the good phagocytic cells surround the bad bacteria and begin to ingest and destroy it by releasing sodium hypochlorite which is actually the main ingredient in household bleach. The dead bacteria is then released into the bloodstream and passed out through the kidneys in urine.

Now what happens when there is a prolonged production of the second hormone cortisol is this: The cortisol represses the digestive enzymes of the phagocytic cells and literally destroys their ability to ingest and anihilate the bad bacteria- leaving the fish vulnerable to attack from all kinds of resident bacteria and parasites.

3. What are common stressors in the aquarium?

Here is a list:

Prescence of ammonia

Prescence of nitrites

Prescence of high nitrates

Fluctuating pH

Changing water temperatures

Handling

Over crowding of the aquarium space (too many fish)

Bullying or breeding behavior

Lack of correct or adequate nutrition

Overfeeding (food left uneaten)

Too strong light/lights on at night

Too little light

Lack of dissolved oxygen

Ornaments that injure or interfere with swimming space

Too strong a current (some fish, not all!)

Over medication and

Wrongly diagnosed medication.

Conclusion

In conclusion. Our fish are designed to survive. They have strong immunity given the right conditions, especially the correct water environment, space and food. If we aim to avoid all the above stressors we have the chance of being able to raise fish with powerful immunities- their best preventative defence against parasites and bacteria getting a hold in the first place.

Written by Trinket

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:oops: sorry its the teacher in me..couldnt resist editing with some black ink.

Now take the red pen away from me :rofl

Thanks :D Pinning this.

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Very usefull! Thanks you two :) I have a question though. Does having your hands in the tank stress them out too? I wash my hands really good before touching anything that goes into the tank (food, decor, etc) and they come up to me to get their food and Romeo sits in my hand.. Could that stress them out though?

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Crystal..a lot of people like to have their goldfish nip their fingers and hands while feeding and cleaning. Excessive rough contact will result in slime coat reduction and definitely would stress the fish. Hand feeding in my opinion is a fun alternative to tame your goldfish. Gentle play with moderation I feel won't stress them.

-Dennis

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Ok thanks! I don't physically go to my fish, they come to me and I dont squeeze or hold them there either so I guess thats ok then :)

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Very good reading, glad you posted it. Thank you.

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Guest Londo

'Stress' can sometimes seem a little vague, thanks to everyone for clarifying it.

But I just have one question, I noticed blackteles included lighting as a possible cause of stress. I'm not quite sure what the guidelines are. I take off the lights for about 7 hours at night because I know plants need darkness to give the light independent reactions time to catch up. I assumed the fish, living under the sort of diurnal conditions that they do, would also appreciate the 'rest'. Is this O.K?

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Yes, it's okay. Lighting causes stress when it is prolonged, like leaving the tank lights on for a full 24 hours. This is because they have no eyelids, so it's really tough for them to sleep with the lights on 24/7. Lighting can also cause some stress if it's too irregular, goldfish like to have a steady night/day pattern. This can be achieved fairly effortlessly with a light timer. :)

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Yes, it's okay. Lighting causes stress when it is prolonged, like leaving the tank lights on for a full 24 hours. This is because they have no eyelids, so it's really tough for them to sleep with the lights on 24/7. Lighting can also cause some stress if it's too irregular, goldfish like to have a steady night/day pattern. This can be achieved fairly effortlessly with a light timer. :)

You say that Goldfish have no eyelids

but I could swear that I saw Wanda blink

am I going crazy???

:unsure:

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Eye movements.:) They don't have eyelids at all.

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Yes, it's okay. Lighting causes stress when it is prolonged, like leaving the tank lights on for a full 24 hours. This is because they have no eyelids, so it's really tough for them to sleep with the lights on 24/7. Lighting can also cause some stress if it's too irregular, goldfish like to have a steady night/day pattern. This can be achieved fairly effortlessly with a light timer. :)

You say that Goldfish have no eyelids

but I could swear that I saw Wanda blink

am I going crazy???

:unsure:

maybe its something like a nictitating membrane? I saw an abstract for a study online where they apparently taught a goldfish a "eyeblink-like" action but I'm not a member of the research journal so I couldn't read the full article to see what they meant by "eyeblink-like"

http://www.ncbi.nlm.nih.gov/pubmed/20006973

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Very good article, thanks for sharing it with us! :clapping:

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I love this article, and the one Trinket wrote too. Stress so often gets overlooked when it is frequently the root cause of fish problems!

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Guest Gen120

awesome thread, thanks for posting it, very informative!

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I wonder if only factors inside the aquarium influence stress levels or if the environment, location of the aquarium can play a role too.

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I wonder if only factors inside the aquarium influence stress levels or if the environment, location of the aquarium can play a role too.

I would think so. My husband just wondered this too, because our QT tank is on the counter over the dishwasher.

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