Accuracy of sexing a hypancistrus pleco (zebra) via venting?

[subconsciousplecoluv]

Hello everyone!
I am here to raise a question regarding the accuracy of sexing hypancistrus zebras using photos of vents/genitals. As most people who want to have a go breeding these fishes would, I have read up on all the sexing/breeding guides available online as well as some forum posts of prospective breeders wanting to find out their fishes' sex.

As most know, the sexing methods surround: amount of odontodes, caving/non-caving behaviour, body and fin shapes. My impression from reading many sexing/breeding posts is that there is a large range and variation with respect to anatomy (eg. many hairy females, fat males, skinny females, and comparing curvatures of fins is arbitrary). Behaviour seemed the most consistent: males will cave all day, females may cave but never defends it but more often hanging "in the woods" nearby. It has been suggested repeatedly by some that venting is the most accurate way to sex a zebra pleco.

A quick search on google images will produce only a handful of images. Many have referred to those images as recommendation/guide to sexing via venting. Here is an example (to the photographer/breeder known as SmithRC, please pardon me for screenshoting the google image).

I have found it difficult to match (sexing) the above image with the behaviour of my current colony as well as the confirmed males and females of my previous colony.

I have bred zebras before. Heres an image of the vent of the dominant male that bred. Lets call him MALE.

Screen Shot 2017-04-08 at 8.44.11 pm.png (197.16 KiB) Viewed 2210 times

Below is the image of the vent of the female that he bred with. Lets call her FEMALE.

I haven't had many plecos before I bred the L046. But the vent of my dominant male definitely did not look like male photos on those online guides. I suspect perhaps its because my male was an older fish (potentially wild caught as well, bought in 2007/8 from a hobbyist who kept them for 2-3years after purchasing them from a LFS). To complicate things, the female vent also did not fit the guide. Yes its more pronouced that the male, but it is very very V. These anatomical features proved true for the other sexed (and bred) fishes in that colony.

Alright. Here is why I am back into the sexing game..


I just got a new colony of zebras.
This is the image of an "unsexed" zebra that caves all day. Lets call it #1.

Screen Shot 2017-04-08 at 8.51.13 pm.png (194.57 KiB) Viewed 2210 times

Here is another image of a second "unsexed" zebra that sometimes cave but mostly prefers to hang around. lets call it #2.

Screen Shot 2017-04-08 at 8.51.24 pm.png (260.88 KiB) Viewed 2210 times

Noticed something?
#1's vent resembles FEMALE, but resembles sexingguidemale (it behaves like a male)
#2's vent resembles female vent in sexing guide (and yes, it behaves like female)
Neither #1 or #2 or Sexingguidemale's vents resembles MALE.

PS: I left out photoshots from above and close up of facial odontodes so we can solely focus on the credibility of sexing via venting.

Any opinions on the accuracy of sexing via venting people?

If you guys have images of vents of the zebras that you have bred (not sexed only, but bred), lets compile it. I don't mean to exclude non-breeders, it is so that any previous opinions given to you on forums/guides may not be proven until your zebra pairs have indeed laid eggs and fertilised it.

[Jobro]

May be difficult on pictures like yours but it is way more obvious in real when you take them out of the tank and into your hands.

They need to be old enough, though.

My experience comes from other Hypancistrus than the Zebra but they are all pretty much similiar.
I picked 4 out of 4 L260 females just by vents. Was a little surprised that it worked myself

[TwoTankAmin]

I looked at the Pics before I read the text beyond the title. I thought the pictures were not of the best quality which makes being certain harder. I agree you likely have both sexes but you have them reversed imo. The top one is male and the bottom one is female based on venting, imo.

Males are more pointy like a V and females are more rounded/bloblike. He needs to get a squirt out but she needs to push out eggs. I am not sure how much credence to put on this. But some folks believe males wile often have a black dot on its bell under the vent went it is out

[subconsciousplecoluv]

hello twotankadmin. the images for MALE, FEMALE, #1, #2 are all in the right positions.

#1 vent is pointy V, which is the same vent as all my previously bred females.. I chart its caving activity twice a day over a long period of time, it caves in one cave 4/5 of the time and a smaller cave 1/5 of the time. its current behaviour point towards a male. (tbh I think it is highly likely a male)

but the issue is, if i were to present my first post to someone who hasn't seen vents before, they will all be able to see the resemblance of #1's vent with FEMALE's vent. (nope, did not mix the images up, checked this for the 10th time and lets put them sidebyside/consecutively so people don't get confused)

without colour:

Screen Shot 2017-04-08 at 8.51.13 pm.png (194.57 KiB) Viewed 2157 times

and.. here is a photo of MALE and his buddy. they are deadgiveaway male anatomy. but ignoring those other male traits, they both have the same vent. (the giant raise platform that has a crater and a small blib):

yeap this one:

Screen Shot 2017-04-08 at 8.44.11 pm.png (197.16 KiB) Viewed 2157 times

Hey Jobro, the ages of all the above zebras are above 3 years of age and they are all above 7cm. Would you mind sharing one or some of your female L260 vents that have bred for you? (or your confirmed male!) I agree it is more obvious when they are in your hands and right in front of you. However, most people used photos as guide or to get advice on forums regarding sexing. Having a collection of photos will help to show the variations in vent anatomy and clarify if it is indeed a fail-proof method.

[subconsciousplecoluv]

He needs to get a squirt out but she needs to push out eggs. I am not sure how much credence to put on this. But some folks believe males wile often have a black dot on its bell under the vent went it is out

interesting! about the Squirting. I wonder if anyone has dissected a (hopefully dead) zebra pleco up to examine the reproductive/digestive tracts and organs. it will be so painful to watch though..

Is this the black dot you mentioned? Do yellow spots around the vent mean anything? (this fish has no obvious genitalia whatsoever..lol)

[TwoTankAmin]

This about what has to come out of each tube. Which one needs to be wider to pass eggs vs more pointy to direct sperm onto eggs>

Here is a gallery of the pictures I took of my Hypancistrus L173b. Each fish was shot as described as above. Some are better than others but you can pretty much see the tubes for all the fish. (The top two pics are the offspring.) http://twotankamin.smugmug.com/Fish/L-173b/n-chr5b

[Jobro]

Hey Jobro, the ages of all the above zebras are above 3 years of age and they are all above 7cm. Would you mind sharing one or some of your female L260 vents that have bred for you? (or your confirmed male!) I agree it is more obvious when they are in your hands and right in front of you. However, most people used photos as guide or to get advice on forums regarding sexing. Having a collection of photos will help to show the variations in vent anatomy and clarify if it is indeed a fail-proof method.

Your welcome

female vent:



female vent:



younger female vent:



younger male vent:



male vent:



Going by headshape can be quite tricky as well:
Same fish, two pictures taken within 1 minute:


I feel like headshapes vary way too much depending on how the fish sits... This is a female btw.

I have to admit it can be pretty tough on the younger ones. but adults are quite easy to vent I would say. Especially if you see the rest of the fish. Now this is with hypancistrus and I tried this on peckoltia, panaqolus and even ancistrus (easy to tell the genders anyway but I looked at the vents for comparison) and I found it way harder.