Tang Police or Tang Nazis?

[fishoholic]

Originally Posted by lastlight

*lays a man-slapping on lance*

+1

I do advocate for tangs to have a decent sized tank to swim in and I often recommend at least a 90g for smaller tangs like koles/scopas/yellows and 180g and up for larger tangs and even more space 8-10 feet long tanks for naso tangs. IMO a baby tang under 2" is not going to need as much room to swim in as when the tang gets larger (over 6") so if you want to keep a baby tang in a smaller tank and plan (and actually do) re-home it then go for it, however the problem is when the person gets attached to the baby tang they have in their small (say under 40g tank) and the next thing you know you see a 6-7" tang who is the same length as the tank they are in, which at that point I will get on a soap box and say that isn't right. However I have seen the smaller tangs koles and scopas in 45g tanks and they seem perfectly fine and healthy so I while I would recommend a 90g to that person I am not going to freak out on them, however if it was a 8" unicorn tang in a 45g I would, but one of the smaller tangs no.

Now I am far from perfect and even admit that while I think bigger/longer tanks for tangs are better I have a 230g which is only 6 feet long and I do plan on adding a blonde naso to it. So really I'm not much better then the person who keeps a yellow tang in their 40g tank. This is a bit of a selfish hobby and while I do believe you should try to do you best to provide a decent home for the fish, there are times when we talk ourselves into adding a certain fish that we know might not be "ideally" suited to our tank.

A quote from the article "The members of the genus Naso and Prionurus are the true open water swimmers; they are the ones that require special consideration." I have to agree with this 100%. When I was cycling my 230g reef tank I saw a great deal on a naso tang he was 2-2 1/2" and I knew I wanted to add a naso to my 230g reef, so the deal was to tempting to pass up. However at the time the tank I had available to house the small naso in while the 230g finished cycling was a 30g cube I knew it was wrong to put a naso (even a small one) in a 30g cube but because I knew a had a bigger home for him to go into in a few weeks I talked myself into it being ok. He was in the 30g for 2 months before the 230g reef finished cycling and he was a dark grey stressed out colour the whole time he was in there. He also swam speractically all over the tank, at the time I convinced myself that he was eating so he was fine. However I didn't even realize the colour change and the (IMO) stressed out swimming patterns until I transferred him to the 230g. After the transfer he was no longer a dark blotchy pattern colour and changed to a lighter solid grey colour and he no longer did jerky swimming movements, he swam across the length of the tank and IMO seemed significantly less stressed.

I think this part of the article is important to point out, so that people do not get the wrong idea from the article "Hopefully you don’t think that I advocate keeping fish in overly-small aquariums, as I do not. I always strive to give my captive fish the best possible environment. The exhibits I use for tangs at the public aquarium where I work range from 450 to 1,300 gallons. What I am advocating for here is a more civil discourse, more careful consideration of measurable husbandry parameters, and less reliance on subjective personal opinion."

[asylumdown]

I would say that given that the aquarium trade removes about 1/1 millionth of the fish from the ocean that the commercial fishing industry does every year, and the damage we do to reefs by removing coral absolutely pales in comparison to the damage drag net fishing, or dynamite fishing, or cyanide fishing does to the reefs of the world, that the ethics of how damaging this hobby is to global ecosystems is a totally mute point if anyone here eats tuna.

Reefs in places that have something to gain from having a steady supply of healthy corals and fish to export to the aquarium trade and regulate it accordingly (Australia and Hawaii for starters) can actually benefit from an active aquarium trade. True not all places are like that, but that's why my elegance coral is Australian and not from the Philippines. Most species of fish on reefs reproduce in numbers greater than the niche market of the aquarium trade could really make a dent in, and in the cases where that's not true, it's usually the research that happens as a result of the aquarium trade that helps us find that out.

As for the ethics of keeping animals in glass boxes - that's always going to be a matter of opinion, but one would think that everyone here had to come to peace with that little conundrum by now.

[Aquattro]

Originally Posted by asylumdown

As for the ethics of keeping animals in glass boxes - that's always going to be a matter of opinion, but one would think that everyone here had to come to peace with that little conundrum by now.

Agreed. I guess my side of the fence feels that even though I've made peace with what I do, I'm not going to try and justify it with some story about research or saving fishies from sharks I am not a friend to the fish of the world (I eat tuna every day), but I'm ok with that.

[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

[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.