Hi all, at what size is it generally easy to tell the sex of juvi bristlenoses? I'm interested in buying a trio of yellow bristlenoses from a seller on Ebay which he says are 3 to 3.5cm long at present I have asked if he could get me a male and female in the trio but because none are showing bristles yet he can't guarantee he can though he will try his best at selecting them by their different shape I thought that by the time they are this size the male should be showing bristles? I don't want to end up with a trio of females!

at that size there is no way you can tell sex. you can have a guess from body shape but i have been breeding these little fellas for years and im still only right about 60% of the time.

The best thing i can suggest is to buy 3, let them grow til they are mature then trade trade for the sexes you need. or buy 6 and sell the excess when you can sex them. generally at about 10 months or 7cms you can sex them but even then one or two have fooled me.

Ok thanks, they're more difficult than I thought then! I may just leave it for now as still have to shift my brown bristlie fry then perhaps I can concentrate on the yellows

was told somewhere that you can tell by feeling the noses. One is soft and the other is harder ( I think)

[quote="Stannyblade"]was told somewhere that you can tell by feeling the noses. One is soft and the other is harder ( I think)[/quote]
Thats intresting will catch some and try? Will reply if ones hard or soft ??
I get 60% right at 5.5 cm at 6 80 % by looking at fins at 7-8 99 %.
Peppermints seem harder but i bought 5 at 3cm tryed for females only, by looking at fins and i think i have 4 females and a male 8-10 cms.
Looking under the body at 6 cms gives a fair idea also.

the hard/soft bits you refer to are the armour plating that give these fish their name (armour-plated catfish). There is differences between the males and the females but again this develops with sexual maturity so if you check too young you will mistake a male for a female. you need to be very careful when doing this as the fish will be stressing out a lot and will be attacking with its spikes which can cause a nasty cut (speaking from experence).

Looking at the under side, down at the naughty bits, is a tried and true method with plecos and there are those who claim to be able to sex some plecos at 3cms. Bristlenose are a bit harder than say, the L333. but when they are a bit bigger its possible. Again, all these traits start to change at about the same time, guessing before then is only that, guessing.

Fin length can be misleading, and varys a lot with bristlnose species.

and like littlebristlenose said, peppermints are very hard.