please help sexing my new Chameleon Whiptails - Pseudohemiodon Apithanos

[jamesleagas]

hi guys first ever post here for me so please be nice ha ha

i purchased these fish yesterday and have been reading up about them, i read its easier to sex when in top condition, i dot suspect these are atm having been in lfs hidden away for quite a while,

id like any thoughts regarding sex if possible? thanks in advanced

not the best pics i understand these where taken in the lfs and then once i tipped out the bags to acclimatise

[Richard B]

Nice species - i'm not good at sexing these though - which LFS was it?

[jamesleagas]

They came from a maidenhead aquatics I was passing by, they've had the twice in 5 years

[jac]

For me they are all female. Just looking at headshape.

Here is a picture of mine to help you see the difference: proven female on the right

[jamesleagas]

thanks for views so far
that female u have above is very attractive looking, do u have any tips for caring for them the best i can? diet, wc routine etc? more pics of your tanks would be very helpful

[Foti]

Congrats on the buy lov these fish too bad I live in Aus iv never seen them fs here !
All the best in getting a breeding group going !

[jamesleagas]

Thank you for kind words

[jac]

that female u have above is very attractive looking, do u have any tips for caring for them the best i can? diet, wc routine etc? more pics of your tanks would be very helpful

She is the only one with brown coloration
They are pretty easy to keep. Just follow the cat-e-log and you'll be fine. Yours need to grow so give them lot's of TLC
I feed them tablets and frozen foods. And I do 3 water changes a week.

Good luck and enjoy your fish

[bekateen]

Here is a picture of mine to help you see the difference: proven female on the right

Hi jac, I'm staring at your photos of your two cats, "proven female on the right" (and thus I assume proven male on the left?), trying to figure out the differences. Please tell me if I'm seeing this correctly:

Compared to your left photo, the proven female on the right has

1. eyes that are set more close together, nearer to the midline, whereas in the photo on the left, the eyes are positioned such that they divide the head into approximate equal thirds from side to side
2. a wider body immediately behind the opercula (in the photo on the left, the body tapers inward more before straightening along the sides, whereas in the photo on the right, there is less tapering of the body before the sides go straight back). Stated another way, if you compare the ratio of maximum head width (at back of opercula) to body width at the leading edge of the pelvic fins, the female has a much smaller ratio, i.e., wider body

(I actually measured these using a ruler placed up against your photos )

Based on the dimensions of the cats' heads in the photos, there does not appear to be much difference in head proportion: The ratio of head length (from behind eyes to tip of snout) to head width (at widest point, measured just behind the eyes) is almost exactly the same in both photos. But because the eyes are so much closer together in the photo on the right, it gives the female an appearance of having a slightly wider head in your picture.

Is this how you would describe the sexual differences in this species?

Thanks, Eric

P.S. To both Jac and Jamesleagas, these are beautiful fish. I've never seen them in any stores in my area and I would love to find them some day (just not now, since I don't have any tank space, but that's another thread! )

[Richard B]

They came from a maidenhead aquatics I was passing by, they've had the twice in 5 years

Which one can I ask - just wondering if it's one known for cats or not?

[jamesleagas]

What length are yours jac? And how fast do they tend to grow?

They were from a store in Solihul

[jac]

@Bekateen; you should not measure any thing from these pictures. They are random taken and not exactly the same in size ect.
The pace of the eyes can also be misleading because of the color difference in the fish, and not forget; the pictures are not in real size.
The only given hint is the slightly elongated headship of the male. Looking from the eyes to the tip of the nose, the male has a slightly longer headshape. Further more I can say that the females have more bodymass, mostly by being gravid. The males are more slender in body shape.
The female shown in the picture has produced eggs and fry in the past. The male is one of two I had the chance to buy a few months ago. I still have to prove my vision by getting them to spawn again I am trying, so bare with me!

@jamesleagas; juveniles grow quick. I have a few at a friends house that are growing fast.
The individuals in my breeding set up are around 15cm.

[bekateen]

Hi jac,

@Bekateen; you should not measure any thing from these pictures. They are random taken and not exactly the same in size ect.

I expected that these pictures were not shown real size, and that's why I relied on body proportions and ratios rather than actual body lengths. I did interpret your photos as being taken from straight above the fish, and I admit that my proportions would be affected if one, but not the other, of the photos you provided were taken from some side angle.

The pace of the eyes can also be misleading because of the color difference in the fish, and not forget; the pictures are not in real size.

Jac, because your photos are so good, I was able to clearly see the eyes and the precise edges of the eyes in the photos. Therefore, I don't think that the photography affected my ability to see the placement of the eyes. However, it is possible that the differences I see in your photos between the male and female may be more related to the individual fish you photographed, than to real or average differences between sexes within this species.

Jac, if you have any other adults (you mentioned one other male, what about other females?), would you mind photographing them from above and sharing those photos so that we can compare the males to the females? Thank you.

Cheers, Eric

[jac]

Jac, if you have any other adults (you mentioned one other male, what about other females?), would you mind photographing them from above and sharing those photos so that we can compare the males to the females? Thank you.

Cheers, Eric

I already did a while ago

http://www.planetcatfish.com/forum/view ... =5&t=41014

[bekateen]

I already did a while ago

http://www.planetcatfish.com/forum/view ... =5&t=41014

Hi jac, I looked at your photos for all six specimens (4 females, 2 males) and obtained several proportions from the photos. The traits I measured were:

1. Maximum head width, measured at back of opercula (HW)
2. Interocular distance, from center of one eye to center of the other (IOD)
3. Head width passing through middle of eyes (HW@E)
4. Head width measured at half the length of the head (HW@1/2HL)
5. Head length, measured from tip of snout to back of opercula (HL)
6. Eye snout length, measured from the middle of the eyes to the tip of the snout (ESL)
7. Body width, measured where the pelvic fins visually emerge from the body (BW)

Here is a summary of my results:
Trait Ratios ....... Females ......... Males
HW/IOD ............... 3.22 ........... 3.22
HW@E/IOD ........... 3.05 ........... 2.94
HW/HW@1/2HL ...... 1.46 ........... 1.61
HW/HL ............... 1.61 ............ 1.45
HW/BW .............. 1.21 ............ 1.39
HL/ESL .............. 1.14 ............ 1.18

The actual measurements are here in the attached image (by the way, the units of the numbers is "pixels" because I was simply measuring pixel distances on the photos).

If you are correct about the sexes of "female 3" and "female 4" and about the sex of "male 2," then from these photos I would conclude that the two most reliable ratios were (1) Head width / Head length (females have proportionately wider and shorter heads than males*) and (2) Head width / Body width (females have wider bodies than males). These two ratios were consistently different between the sexes across all six individuals and they are the differences that you've mentioned previously in your other thread.

Regarding all of the ratios that involved the eyes or the contour of the head (e.g., Head width at 1/2 head length, and eye snout length), you can see there is a lot of variation in these ratios. Overall, your males' snouts were more pointy (they taper quickly whereas the female heads flare out from the snout), but this value was very different for females 3 and 4 compared even to females 1 and 2; females 1 and 2 had values closer to those of the males. Also, the relative length of the snout anterior to the eyes was similar in the females and in male 1, but male 2 had a particularly long snout extending in front of his eyes.

Likewise, the eye spacing is different when you compare females 1 and 2 to females 3 and 4. Females 3 and 4 have eye spacings that more closely match the proportions of males. So maybe the distance between the eyes is something that becomes more dramatic as the fish mature (I admit that I assumed females 3 and 4 are younger than females 1 and 2, since 3 and 4 weren't "confirmed" females, but I shouldn't have made that assumption... sorry).

In the end, I guess all I've really accomplished here is confirm what you've already said - that females have broader snouts and wider bodies than males. Perhaps this was an exercise in futility on my part, but now I'm intrigued by how similar females 1 and 2 are, and yet how different females 3 and 4 are, both from the other females and from the males: Is this simply an example of individual variation, or are these differences due to developmental changes?

Cheers, Eric
* By shorter head, please note that I did not measure body length in any of these fish, so this is not an absolute statement about head length, but only a relative statement about head length compared to head width

[Jools]

Funny I was thinking about doing same. If you look at HW and HL, what would be interesting would be the angle formed by a further line going front the snout to the opercula. I think that would begin to give us a sexing metric range.

Jools

[bekateen]

@Jools,
Is this what you wanted?

The "1/2 snout angle is calculated by treating the right or left half of the head as a right triangle, then calculating the angle at the snout as the arctangent of (1/2 head width)/(head length).

This creates values in the 36-39 degree range. From here, Snout angle is simply double that number, and represents the angle you should measure if you drew straight lines from the snout tip to each opercular corner, and then measured the angle formed.

I'm not trained in classical morphometrics, so I may have used inexact landmarks when measuring the lines, but the math should be good!

Cheers, Eric

[Jools]

I've seen species described with less difference. I think this will be really useful, not just for Pseudohemiodon, in future.

Jools

[bekateen]

I've read that these fish change color with stress level (which I'm not surprised to learn; a lot of animals do). @Jac, I'm curious about the fact that both of your "males," as well as the only "male" labeled as such among the photos on the

Pseudohemiodon apithanos

page, are all black headed, instead of pale headed. I'm guessing that this just a coincidence (if not, that would be a really easy way for @jamesleagas to sex his fish! LOL), but it makes me wonder - if the females are not turning as black as the males in your photos, is it your impression that the males become stressed easier than the females do?

Thanks, Eric

[bekateen]

@jamesleagas, Can you try taking the same measurements on your fish in your photos and see if you can figure out the sexes using the information we've posted here?

[bekateen]

id like any thoughts regarding sex if possible? thanks in advanced

For me they are all female. Just looking at headshape.

@jamesleagas, Can you try taking the same measurements on your fish in your photos and see if you can figure out the sexes using the information we've posted here?

Jac, since you have these fish, and you have a number of them, I'm inclined to trust your judgment on the sexes of jamesleagas' fish. But I couldn't wait - like a kid in a candy store - to see how jamesleagas' fish would come out if compared to the measurements and ratios I obtained from your fish.

Well, here are the results (see photos, each of the fish labeled 1-4), and Oh, this isn't good...

Jamesleagas, according to the morphometrics, all four fish shown in this photo come out clearly as males when head length, head width, and body width are measured and used to calculate the HW/HL ratio, snout angle, and the HW/BW ratio.

Both the HW/HL ratio and the snout angle are based on the same measurements, so we wouldn't expect them to disagree with each other, but the HW/BW ratio offers an independent way to check sex. Also, since the some of the fish have blackened heads, I couldn't make out eye position definitively, so I couldn't check this on 3 of the four fish, but on the one fish I could check (what I called fish #2 in my photo), the eyes are set wide apart, which is more like the males and less like jac's two "definitive females".

Jamesleagas, I don't know the ages of the fish in your photos but I can see from the ruler that your fish are only about half grown, so maybe your fish are just young and as a result their sexually dimorphic body proportions are not fully developed. Also, if you just got these fish from your LFS, the fish might be thinner because of suboptimal feeding at the store - this would have the effect of giving females a more male-like HW/BW ratio (i.e., females would be skinnier across the body, like males). If these factors are true, then this could explain the morphometrics diagnosing your fish as male, when in fact they could be females, as Jac said.

Jac, I don't wish to disagree with your assessment of the sexes of these fish. In fact, I trust your assessment more than my numbers. But alas, if we can infer anything from the body proportions of your six adults, then all four of these fish are males.

I've seen species described with less difference. I think this will be really useful, not just for Pseudohemiodon, in future.

Jools, if these four fish are females, then you can forget using the measurements I gave you earlier as a diagnostic tool!

Cheers, Eric

P.S.

I've read that these fish change color with stress level (which I'm not surprised to learn; a lot of animals do). @Jac, I'm curious about the fact that both of your "males," as well as the only "male" labeled as such among the photos on the Pseudohemiodon apithanos page, are all black headed,

Well, if these are all males, then this photo shows a male that isn't black headed (although 3 out of 4 are - again, do males stress easier than females?). Cheers, Eric

[Jools]

I suspect it doesn't work unless you're dealing with fishes beyond a certain HL (120 - 130?).

Jools

[bekateen]

I suspect it doesn't work unless you're dealing with fishes beyond a certain HL (120 - 130?).

Agreed, although I couldn't begin to guess at which size this would be applicable to this species. Also, remember that I was simply measuring pixels, not real dimensions like mm or inches. Thus, the fact that my measurements for jamesleagas' fish are smaller than for jac's fish is meaningless - his photo may simply be taken from farther away, or at smaller pixels per inch. But fortunately, jamesleagas' fish are photographed beside a ruler; that shows us quantitatively that his fish are nowhere close to full grown.

Think puberty in humans: Body proportions change dramatically as sexual maturity sets in. These fish are small enough that they may be unsexable using morphometrics.

I wish I knew at what size this species starts spawning. If we could get several records of the body lengths of different pairs of sexually active fish, we could identify a minimum body length or head size at which morphometrics could be applied. Jac, how long are your fish (in terms of SL)? You mentioned 15 cm (almost 6 inches) on the previous page of this thread - that's almost two times longer than jamesleagas' fish.

[jamesleagas]

I'm at work atm so quick repsponse for now, 3 out of the four fish I have seen with white/grey coloration on the head as u can see the one in the pic above

Both the larger ones and one of the smaller ones

I'll be online in the morning and will read and respond properly

Thanks for all the time and effort from u guys

[racoll]

Guys, I'm sure you all know this, but you can't infer anything with an n=1 sample size. As you can see, it does not include the bounds of possible variation.

That said, it's an interesting hypothesis, and if we cab get hold of enough images of proven-sex adults, and if we can standardise the data collection*, there could even be a journal article worth writing here.

*there are many variables involved here that need to be controlled for, such as: (1) growth allometry, (2) consistency of landmark choice, (3) physical condition of the fish, and (4) image processing and measurement etc.

[jamesleagas]

If it helps I Dnt suspect that my fish are in tip top condition as the Lfs would not of been feeding them correctly if they are like most Lfs

Probably lived on occasional prima feedings for the last 6-8 weeks that they've been there.

[bekateen]

Guys, I'm sure you all know this, but you can't infer anything with an n=1 sample size. As you can see, it does not include the bounds of possible variation.

That said, it's an interesting hypothesis, and if we cab get hold of enough images of proven-sex adults, and if we can standardise the data collection*, there could even be a journal article worth writing here.

*there are many variables involved here that need to be controlled for, such as: (1) growth allometry, (2) consistency of landmark choice, (3) physical condition of the fish, and (4) image processing and measurement etc.

Rupert, you are absolutely right... Although in my defense I think my sample size is 4 (putatitve) females and 2 (putative) males, using jac's fish as models. (Yeah, Yeah, I know - These still aren't acceptable numbers. But they're better than "1"! )

Moreover, if anybody else likes doing this kind of stuff, maybe someone would want to start examining the oodles of C, CW, L, LDA, XYZ (just kidding, there are no XYZ cats! ). Then we might be able to reach a point where some of the no-name species get species names.

Anyone bored with lots of time on their hands?

Cheers, Eric

[racoll]

Moreover, if anybody else likes doing this kind of stuff, maybe someone would want to start examining the oodles of C, CW, L, LDA, XYZ (just kidding, there are no XYZ cats! ). Then we might be able to reach a point where some of the no-name species get species names.

There's a big difference here between the kind of science that aquarists could and should be doing.

Studying the morphometrics and sex differences in Pseudohemiodon is a great way in which many hobbyists could contribute as part of citizen science.

On the other hand, describing L and C numbers is not something that should be encouraged. The most important elements of biodiversity science are the "what", "when" and "where". Unfortunately, when imported aquarium specimens are concerned, the "where" part of the data is never available with any meaningful accuracy, and the context of the fishes as part of a regional fauna is therefore lost.

[bekateen]

There's a big difference here between the kind of science that aquarists could and should be doing.

Studying the morphometrics and sex differences in Pseudohemiodon is a great way in which many hobbyists could contribute as part of citizen science.

On the other hand, describing L and C numbers is not something that should be encouraged. The most important elements of biodiversity science are the "what", "when" and "where". Unfortunately, when imported aquarium specimens are concerned, the "where" part of the data is never available with any meaningful accuracy, and the context of the fishes as part of a regional fauna is therefore lost.

To a certain degree, I agree fully with you. That is, real "species description" cannot occur in a vacuum without collection information, and more (e.g., providing type specimens to museums, etc.). And in that sense, no amount of citizen science will provide enough detail to allow the proper scientific description of a species. I'll admit that I was being a little tongue-in-cheek when I suggested this - that's why I made the joke about "XYZ" fish.

That said, I would think that citizen science shouldn't be discouraged from trying to quantify these fish that people have access to, with the hope that this data, if properly collected, catalogued, and disseminated, can make its way into mainstream science to facilitate proper species descriptions. In fact, that's part of the definition of citizen science, right?

I mean, yes, nobody will be able to go down to a LFS, buy an unknown fish, take a few measurements, and declare a new species. I think that's your point and I agree. I suppose I'm simply a little put off by your phrase,

describing L and C numbers is not something that should be encouraged.

To me this phrase doesn't sound good because "not encouraged" can also be taken as "discouraged," and I would never want to discourage hobbyists from trying to take their interests to the next level. I presume you don't mean it this way either, but that's how it comes across to me.

Sincerely, Eric

[pleco_breeder]

I'm not trying to get involved in the discussion to any great extent because I'm a bit under the weather at the moment. However, a good historical point of what I think Racoll is trying to say would be

Corydoras kanei

. There was a great deal of discussion on the old catfish-l mailing list, prior to the existence of this site but a lot of the same original members, about the description of this species from aquarium specimens. Even the current species listing in the catelog states the type locality as "Aquarium specimens said to be from near the town of Boa Vista, State of Roraima, Brazil [possibly from the Rio Branco]." This leaves no verifiable locality and, while not doubting the validity of the species, a huge hole of valuable information in any future study. There are a lot of individuals on this site which would be completely capable of the same type of description based solely on measurement/proportion, and a lot more which are not members of this site. If all of those decided to begin tackling L numbers, based on Rio Xingu, Tapajos, etc... which are considered understood collection locations, the quality of the entire family could easily be degraded. I guess what I'm really trying to say is "if it's going to be done, make sure it's done in a way which isn't going to decrease the value of the work done by those who work so hard to provide useable information."

As to the graph done above, I'd like to say thank you for that bit of work. I've considered the angle of the head from tip of the snout to the base of the head to be the most valuable sexual dimorphism feature of a large percentage of species for quite a while, and agree it needs to be taken from known mature specimens. This is a nicer representation of that, at least in method since I don't consider these fish to be of mature size, than I could've put together.

With regard to the original poster, my advice would be to grow them out for another 6-12 months and post pictures when they are in a better condition and more mature.

Larry