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We checked the temp on the 55g tank 2 days ago, and it was down to 72, we turned the heater up real high, and the tank was 76-77 in a few hours.

All of the fish are fine and there is no problems.

It's more the stress from the temperature changes, rather than the temperature changes itself. But yes, a rapid/constant temperature fluctuation has been known to stress the fish enough to the point where they can become more succeptable to ich.

The stress from temp changes can certainly give fish ich, I've had it happen before. My cardinal tetras (fish that prefer temps on the higher end of the tropical range) were living in a tank with a temperature of 74 degrees. I did a water change with even cooler water, and they all broke out with ich. I have to assume that the stress from the lower-than-preferred temp gave the fish ich. I have now raised the temperature, and the cardinals have had no further problems.

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And when he gets to Heaven, to Saint Peter he will tell: "One more Marine reporting, Sir! I've served my time in Hell."

Its not the colder temps or the rapid fluctuation of temperature. Ich is present in all water, its just there. What causes the fish to break out is the stress they receive FROM the rapid temp fluctuations that weaken their defenses till they break out. Some fish are more sensitive to it and break out more often, such as mormyrids, fish without scales, etc. extra care should be taken with these.

This is one of the best written documents on how stress of any kind impacts fish. It does cover temperature stress, but does not discuss actual values.

[link=http://edis.ifas.ufl.edu/FA005]http://edis.ifas.ufl.edu/FA005" style="COLOR: #C000C0[/link]

More info from the book, Fish Disease - Diagnosis and Treatment by Dr. Edward J. Noga, DVM & Professor of Aquatic Medicine, North Caroline State University. Copyright 2000, Iowa State University Press. http://www.amazon.com/exec/obidos/ASIN/081382558X/qid=1111681772/sr=2-1/ref=pd_ka_b_2_1/104-8546798-1461523

DEFINITION OF TEMPERATURE STRESS

Absolute temperature ranges for fish species do not exist because temperature tolerance depends on several factors, including the temperature to which the individual has been acclimated, salinity (for estuarine species), life stage, and reproductive status. The speed of temperature change is also important. Thus, it is difficult to generalize about temperature tolerance because it is influenced by so many factors. However, it is important to be aware of general temperature changes.

Most fish seem to tolerate a rapid drop in temperature better than an equivalent rise in temperature. This is probably due to physiolgical changes that occur with increasing temperatures: metabolic rate (and thus oxygen consumption) increases with temperature. However, oxygen is less soluble at higher temperatures. Thus hypoxia may exacerbate hyperthermia. Also, stress hormone release increases with temperature. Immune function may also take time to equilibrate to the higher temperature, while pathogens can adjust much more quickly; this may explain why many bacterial and parasitic diseases are more common in spring.

TREATMENT AND PREVENTION

Temperature control is feasible in small, closed systems (e.g., aquaria). But, in ponds or other culture systems with large volumes of water, temperature stress is usually economically unfeasible to control.....

It is difficult to give exact recommendations for allowable temperature change because it varies with species, environment, and prior acclimation conditions. For example, fish acclimated to higher tmeperature often can withstand hyperthermia better than the same species maintained at lower temperature. When acclimating fish to a certain temperature, a rule of thumb is that water temperature should not be changed more than 1 C (or 1F) per hour. While some fish may be stressed by this change, many others tolerate even more rapid changes. Fish that are normally exposed to wide temperature fluctuations (e.g., in ponds) are probably more tolerant of rapid temperature change than fish that are kept in a more stable conditions (e.g., thermostatically controlled temperature in aquarium).

It goes on to talk about limiting daily increases to 3C or 3F per day, but I got tired of typing

I still contend that the best way to prevent stress is to minimize changes to 1-1.5F and in cases where you need to change it faster, limit it to that amount twice daily.

All of this must be taken in the context of what is learned about how stress plays a role in fish getting parasites like ich from that other article. Dr. Noga has similar articles in the book, but that link above describes it very well. The immune system just needs time to catch up when a sudden drop or rise in temp takes place.

I'll try to find more in some of my books, specifically on chilling and ich.

Last edited by Cory_Di at 24-Mar-2005 10:31

In a typical water change, similar water conditions should yield no chance for ich to take hold. Temperatures easily fluctuate between several degrees in the wild; so long as the fish aren't introduced to vast differences in water quality, the fish should be fine.

Temperatures may fluctuate significantly in the wild, however, with such large bodies of water, they don't drop 5 degrees in a matter of seconds. I'd have to do some calculations, which I don't feel like doing, but the water temp can only drop so fast, even if the ambient air temp should drop 30 or 50 degrees. Since warm water rises and cold water drops, it takes time for all that volume to mix enough to cause any significant effect. The exception may be fish living in streams where mountain snow is melting, but such fish are likely as acclimated to that as those who are acclimated to the ups and downs of living in a pond.

Also, many bodies of water have temperature stratified. Fish seek alternate strata when they sense unfavorable changes.

Note Dr. Noga's statement that some fish can tolerate 1F per hour, while others cannot tolerate it. Why take a chance?

Even breeding does not require sudden drops. Rather, gradually lowering the temp over several days then doing daily water changes while gradually raising the temp 3F daily (spread out, of course), along with photoperiod is an excellent way to initiate breeding. Of course, lots of their favorite foods help . I just can't see a reason to drop tank temperatures 3,4,5 F in a matter of minutes in a water change. To do so, is risking an ich outbreak.

Looking at Noga's statements on ich, the parasite can live at very low levels on some fish without causing symptoms. It explains how ich outbreaks occur months or years since the last fish or live plant was added. He suggested that some fish may be symptomless carriers. Add some type of stress and BANG!

Last edited by Cory_Di at 24-Mar-2005 11:16

Last edited by Cory_Di at 24-Mar-2005 11:19

For example, fish acclimated to higher tmeperature often can withstand hyperthermia better than the same species maintained at lower temperature.

Found that somewhat confusing, somewhat interesting. Seems to go against reason?

However back to the original question, each of my experiences with ich has been due to a sudden (under 12 hours) drop in temperature. Is that saying that in every case of temp drop there will be an ich outbreak? Obvously not, as each set up is different. But by no means would I ever go around telling people it's fine to have temperature fluctuations in their tank.

^_^
[hr width='40%']"I'm alright, I'm alright
It only hurts when I breathe"

The only time I had ich was when my tank was set on 78 with rams, black neons, yoyo loaches, and an angelfish. The sun came in the windows and heated the room up past 80 in less than an hour and it stayed something like 83-85 all day then at night dropped back down to 72 in the room and the tank heater had to run. All the black neons and rams were coated in spots within a few days. The angel didn't have spots but didn't look all that healthy for awhile. I've also had lots of problems with that tank compared to my other tanks until I doubled the heating and raised the constant tank temp to 82.

I dunno...I never heat my water prior to tank introduction; the tank generally experiences a 3-4 drop in temp (btw, there is no specific maximum level in temperature drop rate for any substance, including water), with no reported ich incidents.

my tank was badly taken by ich when the temp. had fallen to 70 F. but then I installed a heater and brought up the temp. to 78-80 F .In just 2 days the ich had vanished!

In just 2 days the ich had vanished!

Actually that vanishing in 2 days is just part of the life cycle of the ich cyst. [link=Here]http://www.aquatic-hobbyist.com/profiles/disease/freshwater/ich.html" style="COLOR: #EB4288[/link] is another link to read thru. According to numerous sources I've seen it takes temperatures in excess of 95F in order to kill ich. Most tropical fish obviously cannot handle temps of 95F.

^_^

[hr width='40%']"I'm alright, I'm alright
It only hurts when I breathe"

Yes, temp fluctuations would give your fish ich Vict. I have clowns and I live in India where the fish are used to warmer temps all year round except fo winter, when the night time temp falls to 15-18 degrees Celcius. My clowns would break out into ich immediately after a water change during winter. I put a heater, and turned it up real high at 31 degrees celcius. I know that clowns tolerate only upto 29 degrees, but these boys were conditioned to a higher temp all year round, and I had to get it as close as possible.

In winter, I stick to doing a 10% weekly water change against a 25%. The water quality stays okay, though probably not the best, but it saves me the trouble of fighting ich.

I have Babel to thank for this, coz I wouldnt have imagined its the temp fluctuations causing ich.

Thanks Babel

Maybe I am being a stick in the mud and this is all word choice/semantics, but I want to strongly note that temperature variations cannot directly give your fish ich. As listed above several times, temperature changes = stress.

And then, if and only if there are ich organisms in your water, the fishs' immune systems are weakened and may be more susceptible to ich.

But, and this is key, if there are no ich organisms in the water, the temp can swing from ice to vapor and ich will not present itself. (Your fish will die going 100 deg C, but not from ich).
Ich is an organism, it cannot spontaneously appear simply because the temperature of your water changes!

This is no different than when your mother told you to wear a coat in the winter, because you'll get a cold. The act of not wearing a coat and getting chilled does not spontaneously cause a cold virus to enter your lungs -- it does lower your immune system and makes you more suspectible to the germs your sibling is coughing up.

In in responce to the quote "ich is present in all water..."

"What utter rubbish" noted Dr. Burgess (in the Nov 2001 Practical Fishkeeping). Brits don't mince words. Dr. Burgess, an auther of many recent aquarium books, studied Ichthyophthirius multifiliis as his Ph.D. subject at Plymouth University.

I won't repeat all the evidence here, but take a look at
The Skeptical's Aquarist's page on Ich there are seveal 'myths' about ich that are debunked, as well as a very good discussion about the life-cycles and nature of ich itself.

side note to clarify confusion above-

hypErthermia=overheated

hypOthermia= underheated



~jiffy