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I know I've seen information about venting plecos on the site before, but I can't find it anywhere now.

Can anyone tell me if this is a male or female bristlenose.



There are tiny bristles on the head that also go up the snout. The fish is about 3-3.5 inches long.

Bristles up the snout is what I'd say a definite sign of male. I'm not very good at using venting for sexing these.

You may find the FAQ of help too.

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Mats

That appears to be a longfin variety of bristlenose. If that's the case, bristles up the snout definitely indicate male. Female, tank-bred common ancistrus (a. sp. 3 varients) rarely develop bristles at all, and certainly never up the snout.

I rarely rely on venting (because I'm no good at it), but I believe the general rule is female = round/blunt and male = slender pointed. This is much more apparent in females after the first spawn because the vent stretches some after passing eggs.

I've also heard theories about size of pectoral fins for sexing. Basically, males' pectoral fins will reach almost all the way to the ventral fins, whereas the females' fins will be thinner and not reach back as far. Look from above the fish when its fins are fully extended (like bird wings). Supposedly this will work even for fry. Of course, this applies to wild-type fish only, and not longfin BN's. I suppose it makes sense, since the male uses bigger fins for fanning eggs, but I haven't grown out fry to check for certain.

Thanks for the replies -- although not what I was hoping to hear. This is just a regular BN, not a long finned, but it is different from the other males that I have. The bristles are very, very tiny, so I was hoping it would be a female.

I'll look at the pectoral fins, drgold, to see if there is any differences there with the ones that I am sure are male.

Seems like you're tilting at windmills, but I suppose another look won't hurt. But if there are tentacles up the middle of the snout, you have a male. If there are others in the tank, it's possible that this one is subdominant and hasn't grown to his full potential. Female BN's aren't hard to find, especially brown ones. Try posting a wanted ad in the "wanted and for sale" forum and I bet you can score at least one for a good price.

drgold wrote:Seems like you're tilting at windmills

I guess I am. I have seven of these, four regular brown and three albino, and it looks like only one is a female.

Thanks again for your help.

sorry to but in but at how old will a male grow the bristles?

Calsonic, maybe someone else can help with your question because, unfortunately, I don't know the answer.

Barbie, I'm in western WA near Ft. Lewis -- Tacoma/Olympia area. I get up to Seattle once in a while, so I'm hoping I can find a female or two up there.

calsonic wrote:sorry to but in but at how old will a male grow the bristles?

It's difficult to be specific, because it depends on so many factors: Feeding, individual differences, dominance/subdominance etc. But generally, a male has the beginnings of bristles at around 2-2.5" (5-6cm). If not, it's probably a female - try stroking it's nose, it's a pretty good sign. Smooth -> male, sand-papery -> female.

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Mats