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Sexing Formosiana lacustre?

Home Forums Fresh and Brackish Water Fishes Sexing Formosiana lacustre?

This topic contains 0 replies, has 1 voice, and was last updated by  Jrp 6 years, 8 months ago.

Viewing 6 posts - 1 through 6 (of 6 total)
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  • #302052

    torso
    Participant

    Sexing of this slim species seems quite difficult to me. They are adult now and should be easier to jugde, but they are not
    the first pic shows a group some months after incoming. I thought then the upper one could be a female the lower one a male. This clear difference is gone by now as they all feed well

    the first is at 9.8 cm now, the second at 9.3 cm. the presumptive female is most time hanging in the water flow on the front glass. the second one tries to get that position now and then, but is normally pushed away and gives in. As both have a rounded belly after feeding time, I tried some pics and had a look a the enlargements.

    The diffference in the anal structure is clearly to see. But is it significant?
    If the larger is a female it’s possible that females grow larger and are dominant – the others are a bit smaller than the “male” and moving around in the tank.
    does anyone have a clue?
    Cheers Charles

    Attached files

    #347366

    Matt
    Keymaster

    Great photo series Charles and I reckon you might be onto something, but think we’re looking at differences in structure of the vent/genital papilla rather than anus. The anus is normally smaller and placed further forward than the vent, and it looks like both can be seen in this pic, with the anus the tiny depression in front of the larger vent. Can anyone confirm or deny?

    P.S. moved this to main fw forum as seems to be better-placed here.

    Attached files

    #347396

    Jrp
    Participant

    I never got a good look at that area on my fish, and unfortunately they have all since died. However, I was able to sex them by general body shape and markings. My female was larger with a more rounded body and more distinct contrasting markings than the males. The males were also darker overall.
    My female almost looked more like the pics I have seen of F. stigmata than lacustre while the males were more typical lacustre.
    The reason I am sure of the sex is that they spawned for me many times before their health declined and they all died off within a month of each other.

    #347398

    torso
    Participant

    Hi
    thanks for the infos.
    would you agree that the first speciemen is a female, the other a male?
    Cheers Charles

    #347408

    mikev
    Participant

    Sorry, cannot contribute anything to it. My six look identical to each other (and sadly I don’t see them much: unlike stigmata’s they dwell in the back of the tank only making quick runs to the front for food.).
    It seems that sexing “digger” lizards is very difficult in all species… I’m unsure about the sexes of my stigmatas and v.hainanensis either albeit in those cases the groups contain differently looking specimens.

    The uneven chest and body shape in makes me think female… this is very similar to what I see in one of my spotted pseudogastros lately, and in my case it is almost certain that it is an egg accumulation that affect the body shape.

    #347413

    Jrp
    Participant

    QUOTE
    would you agree that the first speciemen is a female, the other a male?

    Based on my fish, yes.

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