Tank size for Tangs? An evaluation...

[Diomedes]

What is natural?

Recently here at Canreef we had a heated debate over the maintenance of two small (3 to 5cm?) Paracanthurus hepatus (Blue tangs) in a 33 gallon tank with a 40 gallon footprint. I unfortunately added some slander and rude comments in an outburst of temper. I decided to make up for it by writing this post. I apologize to those who were offended, and I hope to have the opportunity to offend you again in the future, if only to have the opportunity to apologize again. HeHe Just Kiddin…

In the beginning of Scott Michaels’ book Marine Fishes he states that his “Minimum Aquarium Size” evaluation is the
“minimum suitable aquarium volume for an adult individual of the species. Of course, juveniles and adolescents can be housed in smaller tanks. Activity levels and behavior patterns of a particular species have been accounted for whenever possible…please note that providing as much room as possible will allow any fish to acclimate better…”

Now I understand that this is a MINIMUM aquarium size, but if SM is giving a 12.2” blue tang 100 gallons of space (some of which is filled with rock and sand maybe?) then I don’t understand how putting a 1.5 inch tang in a 40 gallon could cause so much emotion. This is because 12.2 inches in 100 gallons is roughly equivalent to 8.2 gallons of water per inch of Tang. My friend Sumpfinfishe is giving approx. 27 gallons of water per inch of Tang. This is much more space per inch of fish, and that isn’t even taking into account the width of such a huge 12.2” beast. In fact if SM were to give his 12.2” tang as much space as Sumpfinfishe, then he would have written the Min Aquarium size as 330 gallons. So it appears that Sumpfinfishe is giving his tang(s) over 3 times the minimum aquarium size recommended by a world expert. But hey, this is all just the examination of Expert advice. I have a heap of respect for Scott Michaels. He has studied marine biology (as I am doing now – 4th year), and can take some very very pretty pictures. But how did he come to his values for Min Aq size? I don’t know…All I know is that he puts a 7.5” tibicen angel in a 20 gal, a 45” (~4.9ft!!) moray in a 30 gal, a 2ft Coris Wrasse in a 135gal, a 20” Niger trigger in a 75, etc etc etc and the list goes on…Troy has recently expressed regrets over Scott Michaels Minimum Aquarium sizes, and upon closer inspection this would seem to be pretty darn accurate. But SM still has my devotion…his Reef Fishes Vol One is a beautiful book that shows the true depth of his knowledge. I also examined the Dr Burgess Atlas of Marine Aquarium Fishes and I found similar (and sometimes worse IMO) ratings for tank size versus adult length. So where does this all lead? Do I have the magic number of gallons per inch of tang? No, because if I did I would be up in Anchorage Alaska eating dinner with Dr. Shimek. We all have to trust our judgement and kill fish in order to learn. (~JK)

But this does go back to an important question for me…What is natural for a marine fish? In light of recent debates on this board and others, it seems to me that the question of what is natural for our fish (tank size, flow, feeding, water quality etc.) is always going to be a hot topic.
What is natural for your marine fish? Let’s first look at the factors that affect natural behaviors of fish in the wild:

1)Search for food (foraging, grazing, hunting etc.)

2)Competition with same species (intraspecific) and with others (interspecific)

3)Predation (actions taken to deter something from eating oneself – schooling, hiding etc.)

4)Reproductive needs (courtship, nesting, harems, schooling etc.)

5)Disease/Parasites (cleaning stations etc.)

6)Seasonal/Climatic environmental changes (tides, storms etc.)

Now how many of these factors influence a fish once it is in your aquarium?

1)They don’t have to search for food – in fact they probably are trying to get away from it half the time (HeHe)

2)They do compete with each other, but because of the enclosed space the competition is abrupt and usually one fish achieves dominance very quickly…after all there are only so many niches in your aquarium…mysis, brinnies, etc.

3)Once the fear of being eaten wears off (this takes a while in some cases) this behavioural stimulus is no longer present…until the hobbyist buys that cute little grouper.

4)Reproductive needs cannot be met (for most species) in most hobbyists’ aquariums. Does the drive to reproduce still effect behaviors? Sure. How? Don’t know, aren’t even close to understanding.

5)Yes Diseases and parasites shape behaviors in our aquaria. The fish tries to get away, can’t, then either dies or is cured.

6)Tides/Storms etc. don’t make an impact in most people’s tanks. Now power outages though….

So running down the list, there are very few things happening naturally in a typical saltwater aquarium. So what is “Natural” for fish in the wild may not be natural for fish in the aquarium. Look at Cats…is it natural for them to sleep 22 hours a day in the wild? What behaviors do they exhibit in the wild? How much territory do they roam, what food do they eat etc.? The point I am trying to make is that we have to be happy at the present time with as much space as we can afford to give our fish. I just use common sense to make up for my (and anyone else’s) lack of concrete knowledge on how much space a small tang needs…is he happy, eating, frolicking? I tend to worry about bringing out the life on my rock, maintaining properly unpredictable flows etc. But hey that’s my opinion, and I am sure many of you will disagree.

[Troy F]

Good post Diomedes. Your math equations have taken the tang/surgeon fish debate to a new level. You are not going to convince me that any surgeon fish belongs in a tank of that size. I know a few other people you'll never convince as well.

You're post makes some really insightful points that I hope most hobbiests have already considered and accepted. Our tanks aren't a natural system, no matter how hard we try. Most species don't reproduce in our aquariums and alot of them probably have seasonal urges. When you consider that reproduction is the second most important drive (after eating) in nature, it makes life look pretty stressful for our tank inhabitants. But, like you said; we don't understand much about that. If we keep fish in an aquarium we are removing them from the many activities they'd be doing naturally. We do know certain things about a lot of the species. One of these is size and swimming behaviours. Since we have control over this key issue, why not do our utmost to provide the best environment possible? For tangs and surgeons, doesn't this mean a reasonably large tank at the minimum, and a huge one if you can? You used Dr. Shimek's name so I'll point out that he won't add any fish that isn't locked to a small piece of territory in the wild. This eliminates all surgeons and tangs from the equation, in his view.

Back to the numbers, what about when (if) these fish grow? Does the equation still work out when you put those fish into the 60gal aquarium? Is everyone that buys a fish, that will eventually be to large for their system, going to be able to find a home for it that'll be suitable? Sumpinfishe hasn't actually. Two large hepatus surgeons in a 60 doesn't quite cut it for my ethics. I don't know anyone that would want a 8" hepatus tang to add to their system, so unless I can provide a home for one for its entire life, I won't buy one. That is my belief.

As for Scott Michael; I express no regrets about his recommendations. If people were to live by them, we'd have a more ethical hobby. Personally, I'd give a bit more room for large swimmers than he recommends in certain places but I'll defer to his experience, education and "pretty picture" taking skills on the subject. If I'm not mistaken, he is working towards a PhD in ichthyology. When you take his education and experience into consideration, I think they add up to more than a degree in biology and a good eye for pictures.

A wild cat in captivity would do very little differently than a domesticated cat but if you didn't feed it, look out. Wolves vs. dogs would have been a better analogy don't you think?

[Aquattro]

Originally posted by Diomedes:
But hey that’s my opinion, and I am sure many of you will disagree.

<font size="2" face="Verdana, Helvetica, sans-serif">I can't really see anything to disagree with. BTW, I'm starting a new authority group called the anthias police....anyone want to join?
[img]tongue.gif[/img]

[sumpfinfishe]

Wow! I'm speachless
Looks like someone has been doing some homework.
Thanks for your educated and insightful view. I would like to add only one comment to this post: Aquarists are pragmatic if nothing else,and systems and techniques that prove to be the most effective,despite contradicting popular and scientifc views, almost always become the prevailing practice over time. Home aquarists have no economic or philosophic need to follow a "company line" or to stay within boundries of any particular technology or methodology. We do what is necessary to maintain the animals and plants we admire in our own little "captive oceans" and we are constantly pushing back the boundaries of knowledge and technology in our quest. The cutting edge of aquarium technology is often found in the home tanks of aquarists rather than in scientific laboratories or huge public aquariums. Martin A. Moe,Jr.

[ 19 September 2002, 09:53: Message edited by: sumpfinfishe ]

[Troy F]

SFF, what does your Moe quote [img]smile.gif[/img] mean in regards to the discussion?

[Bob I]

I will start by saying that a fish having a brain the size of a pea cannot be happy or unhappy. It can be comfortable or uncomfortable though. With that in mind I will say that I have kept tangs in a 36" tank. I found that a decent sized tang looked distinctly uncomfortable. I did keep a very small Regal Tang in a 36" tank. It did fine until it reached 3" in size. It then began to look uncomfortable. I then took it back to the LFS where it was placed in an eight foot tank. It looked better there. Those are my observations for what they are worth.

[ 19 September 2002, 10:05: Message edited by: Bob Ipema ]

[stephane]

I bet this tread will finish in a kids war ;)

[Aquattro]

My personal opinion is that if a fish in a tank has to turn around after encountering a glass pane, the tank is too small. Sometimes we're willing to impose a certain level of sacrifice on a fish for our own personal viewing pleasure. If you don't think Tangs belong in a tank, great. If you do, nobody on any Internet board is going to change that. I keep two tangs in my tank; are they happy? I doubt it. Am I a good person for keeping them there? I doubt it. I have bought the largest tank I could afford but they still hit the glass and turn around. Some people keep angels, anthias, triggers, etc, in tanks that are too small and still insist on attacking tang owners. Do tangs belong in 33g tanks? Probably not. Is a 180 really any better, compared with the home we took them from? No. Does anyone want to keep reading my rambling? No. Bye [img]tongue.gif[/img]

[sumpfinfishe]

To answer Troy's ?
What I'm trying to say is that I would not impeed a fishes growth or health if I knew I was doing so. Yes, I do keep a fish that can get very large in adult size, however I would never keep a fish in my reef beyond it's rate. When I trade this fish to my l.f.s. or to a friend it will be going to a larger home-you have my word on that. However I see no harm in keeping a fish of this size(3cm)and growing as long as it appears healthy and happy. I also keep a tang in my reef to study it's behaviour not just because of it's beauty. As to Moe's comment, well it appears that some aquarists do not see my point of veiw, however I feel that as long as this type of fish is a juvinile there is nothing wrong with my actions. I read in my previous post that someone purchased a 1.5 cm juvnile tang for a 70 gal tank and that it had died by being caught into the overflow. So my point is: whats better, myself raising a juvinile tang until it's large enough to go to a new home or another aquarists getting the same tang and loosing it to an overflow or being consumed by larger fish. I could say no, and not purchase another baby tang so then what- it could die in a tank too large or from being kept in a l.f.s. holding tank as no l.f.s. is going to ship back a fish because no one wants to purchase it. Happy reefing, sff [img]smile.gif[/img]

[Diomedes]

Yeah, I think trading in fish to an LFS is a reality, and has been one, for some time...I didn't start with a 180, so I had to trade fish in or give them to other hobbyists that had larger tanks. I would keep a small 1 to 1.5 inch blue tang in a 33 gallon, but when it got to 2.5-3 inches I would trade it up immediately. Troy, you said "We do know certain things about a lot of the species. One of these is size and swimming behaviours" I agree on one level, but the point I am trying to make is that "swimming behaviors" are searching for food, initiating/fulfilling reproductive needs, competeing for resources, escaping predation etc. The amount a fish swims in the wild is determined by these factors. Now since we have eradicated or changed these 4 needs doesn't that also change the behavior used to fulfill them? I know we differ on many of these points, but this is not homework, as Sumpfinfishe alluded to (the calculations were ;) ) but sound ecological theory that we are taught...when you take away the influences in the wild that produce natural behavior, what behavior then becomes natural for an organism? I can't say I know, I just think it is an interesting question...Thanks for your input on my question though, I hope Stephane is Wrong about the kids war :rolleyes: