Sexing Bristlenose Plecos

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enrique4jc

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Original poster
Oct 17, 2006
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Eric
When do male bristlenose plecos start developing their bristles? Is that something apparent right away, or do they need to reach a certain size for them to start to grow? I have four, probably about an inch and a half long, but none of them are showing any bristles yet.
 

fishorama

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Jun 28, 2006
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Male bristles can be late developing...or not so much. I've noticed the "red back of head" to be at least as good for sexing males as bristles...but YMMV (your mileage may vary). At an inch & a half there barely into either way of telling...patience...they'll get there eventually.
 

authmal

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Aug 4, 2011
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Phoenix, AZ
Mine was about half grown when he started sprouting bristles. So, about 3 inches in length.
 

FreshyFresh

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Jan 11, 2013
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I started with two super tiny and skinny BN plecos from a LFS. One of them grew big, ugly and bristley, the other is not as big and no bristles after a few years. The big one is skittish, rarely seen and will chase the smaller one away. The other is out and about and not skittish at all. This pair did breed as I have 3-4 other small ones cruising around in my planted 55g. I feed them mini cucumers once or twice a week, as well as occasional omega one sinking wafers.

I still don't know which is male and which is female.
 

fishorama

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Jun 28, 2006
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LOL, J joel ! The big bristley 1 is male...& since you've had fry, the smaller smoother 1 is female.

Some females do develop small bristles but not the red head spot.
 
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authmal

Pseudonovice
Aug 4, 2011
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And tending to the eggs, whether they successfully hatch or not, is probably what he's doing, and why you don't see him as often.
 
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FreshyFresh

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Here's a zoomed in pic of one of my little guys or gals?


The tank from a few feet away. The anubia in the middle is getting so big it's flopping over.
 

fishorama

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Jun 28, 2006
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I know some male plecos get "hair-like" bristles on their pectoral spines & some even on their bodies or from the gills. I'm not able to access planet catfish right now & can't remember what those are called (odontodes?) or if females can get some too.

Joel, yours seems to have them
 
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