Tang Police or Tang Nazis?

[Youngster Dan]

Interesting read.

I only have one little issue with the article, with regards to measuring cortisol levels in the fish. It was stated that there wasn't really a difference in cortisol levels between captive fish (at various tank sizes) and fish in the "field". Now, I'm assuming you have to actually handle the fish to get a blood/cortisol sample?

Wouldn't the actual act of catching the fish induce stress (ie elevated cortisol) and so this stat is completely misleading? As every fish being tested is at an artificially elevated level of cortisol, and it being nearly impossible to take a baseline measurement?

[Aquattro]

Good catch Dan!

[asylumdown]

Originally Posted by Youngster Dan

Interesting read.

I only have one little issue with the article, with regards to measuring cortisol levels in the fish. It was stated that there wasn't really a difference in cortisol levels between captive fish (at various tank sizes) and fish in the "field". Now, I'm assuming you have to actually handle the fish to get a blood/cortisol sample?

Wouldn't the actual act of catching the fish induce stress (ie elevated cortisol) and so this stat is completely misleading? As every fish being tested is at an artificially elevated level of cortisol, and it being nearly impossible to take a baseline measurement?

I haven't read the article yet, but in my field (primate studies) we measure cortisol in feces and urine, with urine being the ideal source (try running through the forest with a giant funnel held over your head...). It's one of the easier hormones to study because of that fact actually. Not sure how they got their sample, but it seems to reason that they can probably get it passively

[daniella3d]

It may take a while before the cortisol level rise after a stress so they might have had plenty of time to take a sample without getting a stress response right away? could be.

then it could be that the fish returned to a normal level of stress after being handled so the stress hormones did not really rise. Maybe it take a constant amount of stress for this hormone to really show higher?

just my thoughts on it as I was wondering about the same thing when I read it.

Originally Posted by Youngster Dan

Interesting read.

I only have one little issue with the article, with regards to measuring cortisol levels in the fish. It was stated that there wasn't really a difference in cortisol levels between captive fish (at various tank sizes) and fish in the "field". Now, I'm assuming you have to actually handle the fish to get a blood/cortisol sample?

Wouldn't the actual act of catching the fish induce stress (ie elevated cortisol) and so this stat is completely misleading? As every fish being tested is at an artificially elevated level of cortisol, and it being nearly impossible to take a baseline measurement?

[don.ald]

Originally Posted by daniella3d

It may take a while before the cortisol level rise after a stress so they might have had plenty of time to take a sample without getting a stress response right away? could be.

then it could be that the fish returned to a normal level of stress after being handled so the stress hormones did not really rise. Maybe it take a constant amount of stress for this hormone to really show higher?

just my thoughts on it as I was wondering about the same thing when I read it.

statistics, well, they are just statistics! use them to create an argument/article and then defend it.
one can use this stat to show that fish are under constant stress...captive, in nature, or while being handled.
all i know is that the sale of tangs have increased dramatically since this thread was started

[shrimpchips]

http://www.reefmonitor.org/documents...rinol.%202.pdf

They do an assessment of cortisol and corticosterone levels from fecal matter, and find that baseline levels of aquarium acclimatized fish and reef dwelling parrotfish are not statistically different.

As for the testing of fecal matter vs direct (blood) measurement, they do both to validate the former method, and find that pooling fecal matter is an acceptable and useful metric for assessing stress hormone levels.

[Mandosh]

Originally Posted by daniella3d

It may take a while before the cortisol level rise after a stress so they might have had plenty of time to take a sample without getting a stress response right away? could be.

then it could be that the fish returned to a normal level of stress after being handled so the stress hormones did not really rise. Maybe it take a constant amount of stress for this hormone to really show higher?

just my thoughts on it as I was wondering about the same thing when I read it.

From what I know, cortisol levels in the average fish reach the highest levels around an hour after being stressed.

[shrimpchips]

Originally Posted by Youngster Dan

Wouldn't the actual act of catching the fish induce stress (ie elevated cortisol) and so this stat is completely misleading? As every fish being tested is at an artificially elevated level of cortisol, and it being nearly impossible to take a baseline measurement?

both fish are presumably caught and handled so that effect should not be a confound. If they can see a difference, and there's no change to their baseline measures (while they might not be true baselines), then it's a fine measure.


And the citation is more than likely to be generalizable to other fish - besides, it certainly isnt the biggest generalization of the literature. Assuming one large ref dwelling genus with a similar behavior acts and responds similarly with Tangs isn't a bad assumption.

[Chin_Lee]

Is anybody willing to create a poll listing off the number off fishes that you ESTIMATE that you have bought and died while in your care? If I were to create this poll, I wouldn't even give the option of 0-10 because that is not realistic. And whatever choices anybody made, I would multiply by 1.5 to get the more accurate true numbers.
Put it bluntly, we all contribute to the practice of sacrificing animals for entertainment. So regardless you give the fish a 50 or 100 or 200 gallon tanks in comparision to their natural habitat, we are only trying to reassure ourselves that we are doing the right thing.

[daniella3d]

Only one for me since I started a year and half ago and that was a green mandarin that was killed by a yellow tang

I sold the yellow tang. Shame because that green mandarin was with me since the begining and was fat and healthy eating white worms, bloodworms and fish roe. I have the female remaining but never again a yellow tang for me.

Now the most important thing in my tank is no aggression and any aggressive fish is sold.

The worse thing to do to fish is not doing quarantine and letting them live with parasites.

Originally Posted by Chin_Lee

Is anybody willing to create a poll listing off the number off fishes that you ESTIMATE that you have bought and died while in your care? If I were to create this poll, I wouldn't even give the option of 0-10 because that is not realistic. And whatever choices anybody made, I would multiply by 1.5 to get the more accurate true numbers.