The Great Tang Survey Results!

[Matt L.]

Well, it has been some time (almost three months to be exact) since the 2009 Great Tang Survey, but I needed to find a block of time where I could go through the results by hand and analyze them. I will update this thread as I continue to analyze the data, although some conclusions are directly available from the results.

145 people from the club participated, of which 125 were serious responses. Sadly, 20 responses had to be rejected because they were either blank, lacking answers to all but the first question, and/or obvious hoaxes.

Before presenting the results, it is important to discuss the significant flaw in this survey: it was voluntary. Tangs are, in my opinion, the most abused fish in this hobby. One cannot discuss tang and tank size without bringing husbandry into the discussion. It must be assumed that people would be less willing to voluntarily disclose poor husbandry practices. Most of the rejected responses were from surveys that initially identified species, but terminated the survey at the first question of size. It also can be assumed that the better aquarist is not only willing to voluntarily disclose information, but likely here and active on the boards to begin with. So I imagine that an entire region of what would generally be considered poor husbandry was not caught by this survey.

With that disclaimer, the results are as follows:

1: Tang Species Being Kept.

Looking at the results, the distribution of fish kept by board members is fairly ordinary. The most frequently kept species are the Yellow (Zebrasoma flavescens) and (Hippo) Blue (Paracanthurus hepatus), with smaller numbers of Purple (Zebrasoma xanthurus), Powder Blue (Acanthurus leucosternon), Naso (Naso elegans or Naso lituratus), Scopas (Zebrasoma scopas), and Desjardini Tang (Zebrasoma desjardini). 40% of all tang individuals reported are Zebrasoma spp.

 

[Cherokee_Dude]

Excellent work!
Small Q - How come the unicorn tang shows up in the Pie chart and not the bar graph? Are there any differences in the results between the two?

 

[Matt L.]

There is an error, in that the two graphs do not match. This is the problem with using attachments instead of links, in that I have no way of going back and editing the attachment after the fact, whereas I can swap a linked image out.

If a moderator would please delete the attached images in the first (original) post, that would be great. I have rechecked, and these are the latest versions (one of the other two is from the first set of data only: note 26 versus 34 blue tangs).

I have also switched to PNG format so the images are much clearer.

Graph 1a: pie chart distribution of surgeonfish species owned by survey respondents.

Graph 1b: bar chart showing number of surgeonfish of each species owned by survey respondents.

Matt

 

[Matt L.]

Great Tang Survey Results Continued

The first question this study intended to answer was which species of surgeonfish are being kept by local hobbyists. The answers was that the most common and hardiest species of surgeonfish in the trade tended to be the most frequently kept locally.

It cannot be concluded whether the surgeonfish species selection habits of local hobbyists represent those nationally, as no survey was taken of hobbyists around the country. I do consider it highly likely, though, that the distribution of local species is representative of a national whole. Perhaps a wholesaler would be willing to share their sales values with us?

This study hoped to capture much more than a simple headcount of surgeonfish species. It was hoped that some light could be shed on how tank size affects growth rate, health, and survivability, which brings us to the next portion of the survey...

2. Tang Size and Tank Size:

The next set of results are the survey of tank sizes. As shown in the graph, below, the distribution of tank sizes used to house surgeonfish is fairly straightforward, with commonly manufactured 4ft and 6ft sizes representing the majority of the responses.

The graph below shows the size tank people put the fish in to start, and the last tank the fish was in, alive or dead. There is some, but very little shift upwards.

For people keeping tangs, the most common tank size chosen was a 180, followed closely by the much smaller 75.

49.6% of the club has or had their tang last in a 55gal through 120gal tank, and 27.2% of the club last had their tang in a 125gal through 180gal tank. Altogether, just over three quarters (76.8) of the club keep their surgeonfish in tanks in this size range.

While 14.4% of the tangs were started off in tanks smaller than a 55gal, only 6.4% of them ended there. So if you're keeping your tang in a tank smaller than 55gal, then you're definitely in the minority.

But volume doesn't tell the whole story. What's wrong with keeping a tang in a 54gal... if it is a 1 inch hippo?

It has long been noted that tangs desire swimming space more than swimming volume; large open stretches are desirable for just about all species. The study also surveyed tank length, both the length of the starting tank and the ending tank.

The following graph shows which length tanks hobbyists put their fish into. Because there was very little change in tank size, there was even less change in tank length over time, so only the starting tank length was captured.

As can be seen, most hobbyists (48.0%) in the club put their tangs in 4ft tanks*. Some 25.6% of the club placed their tang first in a 6ft tank.

So again, if you're keeping your tang in a 3ft or smaller tank, you're in the 26.4% minority. But that is a sizeable minority, and again, the question comes up: what does a 1" blue hippo tang care if it is in a 3ft or 8ft tank.

Therefore, I derived the metric of relative length. This is the length of a tank divided by the length of the fish. the higher the number, the longer the tank is in relation to the fish.

The following graph shows the relative length of the tang when it was added to the tank.

Most Boston Reefer hobbyists have added their tangs small, as the length of the fish is most commonly (93.6% of the time) one twelfth the length of the tank, or smaller. A minority of hobbyists (6.4%) has added a tang one twelfth the length of the tank, or larger.

Relative lengths of 12 to 18 are the most common, but the next most common relative length is 24 to 30, meaning the tang was added to a tank 24 to 30 times the length of the fish.

The next question is: does relative length have any effect on health? A new post will have to be started...

* Because this proportion agrees with the proportion of hobbyists who have tank volumes between 55gal and 120gal (49.6%), we can assume tank sizes are most certainly standard. This will help us with data analysis later.

 

[JohnK]

Nice work.

Will there be data for longevity vs other factors?

 

[Matt L.]

Nice work.

Will there be data for longevity vs other factors?

Yes. It takes me time to put this all together and into a post. I'm working on longevity next...

Matt