Fluctuating Temperature at Night..

[nc0gnet0]

I understand what your saying, but I dissagree. I think that the healthier the fish is, the better able to withstand stress it will be. I don't believe that allowing them to experience stress will condition them to be able to better withstand stress in the future. If it did, fish that were kept in less than desirable conditions would toughen up and have fewer problems over time, but I don't see that happening. The people who take the best care of their stock, paying attention to the smaller details of keeping them stress free, will usually have the healthiest fish.

This is an interesting argument, however, a bit of a flawed one. All fish expeirence stress. If you feed your fish they get stressed. If they live with other tankmates they get stressed. When we do water changes they get stressed. When we aproach the tank they get stressed. I could go on and on. I fish that has lead a totally stress free life that is suddenly stressed would problable have a coronary right on the spot. . At issue is the DEGREE of stress we are talking about. We condition our fish to except us, to except our constant intrusion into their tank when we do water changes. I do not see this as being any different, and on a stress meter would rate much lower than a routine water change IMHO.

If it did, fish that were kept in less than desirable conditions would toughen up and have fewer problems over time, but I don't see that happening.

It does and it has. Our tanks themselves are less that desirable conditions. We have also adapted them to except a much greater variance in water conditions. Technically speaking it produces a geneticaly stronger fish over time, at the expense of a higher mortality rate of the weak. But, what happens when we as fish keepers go beyond trying to replicate nature and start raising our fish in a germ free bubble? This is great in the short term as we expierance less losses in mortality, but allows genetically insuperior fish to thrive and breed. It's an intereting debate for sure.

[Jhhnn]

I don't think that I want to expose my fish to more stress than necessary, because resistance to a specific stressor doesn't confer resistance to others, and because that kind of resistance is only expressed in a survival of the fittest scenario over generational time.

If I weed out fish that can't withstand wide temp fluctuations from the gene pool, for example, I'll lose a lot of them, and it won't make them or their offspring more resistant to disease. If anything, living in stressful conditions will render them more susceptible because they're already weakened by stress. Nor will exposure and acquired immunity to one pathogen confer immunity to others. Just because I had chicken pox as a kid doesn't mean I'm more resistant to catching a cold, for example.

Mammals enjoy the evolutionary ability to pass on acquired immunities from mothers to children with antigens transferred in milk. The whole mechanism isn't well understood, but known to exist by the scientific community. I suspect that discus may well share that ability when fry graze on parents' slime coats, which would transfer resistance to specific disease organisms but not to other environmental stressors.

Cumulative effects from different stressors shouldn't be underestimated, either. It's the same with people- being cold, undernourished, overworked, breathing bad air and living with high anxiety levels makes us vulnerable to disease organisms.

Yeh, sure, surviving such ordeals can make us emotionally tougher, but that doesn't really apply to discus...

[nc0gnet0]

I think your greatly over-estimated the amount of stress caused by a 2 degree temperature drop over an 8 hour period of time. In nature this is called night time, a totally normal occurance. If it was a two degree temperature drop over a course of minutes, then yes we have added an unnecessary stressor. Temperature fluctuations in water temperature are actually a trigger in many species of fish that induces spawning.

If I weed out fish that can't withstand wide temp fluctuations from the gene pool, for example, I'll lose a lot of them, and it won't make them or their offspring more resistant to disease.

Jhhnn, I never claimed that becoming acclimated to one stressor would increase resistance to another, not quite sure where that came from. And we are not talking about wide temperature fluctuations, we are talking about two degrees over a period of 8 hours.

Nor will exposure and acquired immunity to one pathogen confer immunity to others.

Immunity no, but an immune system that hasn't been used will not function as well as one that has. But I digress, that argument is more suitable for another thread, this one applies to a temperature fluctuations at night.

[kaceyo]

"Cumulative effects from different stressors shouldn't be underestimated, either. It's the same with people- being cold, undernourished, overworked, breathing bad air and living with high anxiety levels makes us vulnerable to disease organisms."
Jhhnn.

This sums up what I am saying very well. First, I don't think a 4 to 5 degree variation is a small one. Even so, All by itself, it would probably pose no threat.
But given all the stressors our fish are put through, anyplace we can reduce that stress is benificial.
We are told over and over that reducing stress is the key to keeping our fish healthy, yet people tend to look at stressors on an individual basis, judging each to be too small an issue to cause problems. But taken as a whole, It is one of the biggest problems we face in keeping the fish healthy.

[kaceyo]

I think your greatly over-estimated the amount of stress caused by a 2 degree temperature drop over an 8 hour period of time. In nature this is called night time, a totally normal occurance. If it was a two degree temperature drop over a course of minutes, then yes we have added an unnecessary stressor. Temperature fluctuations in water temperature are actually a trigger in many species of fish that induces spawning.

I agree, two degrees is less of a problem, though my understanding is that it gets up to 5 degrees variation. I have done a "cool wc" many times to induce spawning, but it's the stressors that go on day after day for long periods of time that I'm concerned with. Besides, we are talking about fish in captivity, not fish in their natural invirons.

Jhhnn, I never claimed that becoming acclimated to one stressor would increase resistance to another, not quite sure where that came from. And we are not talking about wide temperature fluctuations, we are talking about two degrees over a period of 8 hours.



Immunity no, but an immune system that hasn't been used will not function as well as one that has. But I digress, that argument is more suitable for another thread, this one applies to a temperature fluctuations at night.

I have to disagree. If we were talking about bacteria that a body can build resistance to once it's experienced it, then that argument would apply, but a healthy immune system that hasn't been worn down by stresses will react better than one that has.

[nc0gnet0]

Actually it is a 2-4 degree temperature fluctuation. My take on his readings were he was posing a guess based on his readings of a small in tank glass thermometer.

I guess the real argument here is not if stressing your fish is bad, but if such a fluctuation over the course of 8 hours actually indudes any stress, and if so how much? Or does it merely replicate what happens in nature? I know in the past I have during the course of a water change added water that was 2 degrees cooler and or warmer then the tank temperature. And rather than swim away from the cooler/warmer water, they all came over and played in it.

[nc0gnet0]

I have to disagree. If we were talking about bacteria that a body can build resistance to once it's experienced it, then that argument would apply, but a healthy immune system that hasn't been worn down by stresses will react better than one that has.

But you see, this is the problem with your argument. You are taking a worse case scenario in which you are techinically correct, however, it is arguable if it applies to this scenario. I don't doubt for even a second that an immune system that is worn down by stress would function worse than that of one of a fish that wasn't worn down. But you have just framed the argument ( by making the leap by assuming that the temperature fluctuation indeeds adds a significant amount of stress) to make a point.

[kaceyo]

Sometimes we just have to agree to disagree. I'm sure there is some truth in each point of view.

[nc0gnet0]

LOL, I will say this, if it is a fluctuation of 2-3 degrees I wouldn't give it much worry. However, if it was in the 4-5 degree range, then I would begin to become concerned. That being said, I would start questioning my heaters reliability and its ability to adjust to different ambient temperatures.

[XeBurnout]

Kaceyo,

Even though I stand by what I said before, it's hard to argue that you are wrong. There is a lot of truth in what you say. Since your position is that when you maintain the optimum conditions for a healthy fish then that will give you the greatest chances for a healthy fish, and my position is toughening them up a bit will give you the greatest chances of the fish being able to withstand some stress we may be on a wee bit of a different argument.

Like I said, even though I may go with a different tactic, I would never say you were wrong.
Especially since my way entails more risk, which of course you must factor in.

Respectfully,
Phil

[kaceyo]

I respect that and the position you and others take on this issue. Sometimes two opposing views can still be true. If it works for you, then it's right for you.
Thanks,

[David Rose]

I respect that and the position you and others take on this issue. Sometimes two opposing views can still be true. If it works for you, then it's right for you.
Thanks,

+1 Well said!

[Bree7]

Thanks for all of the great advice, guys! I see truth in both sides, and I'll take it all into consideration.