[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: bristle nose plecos

Jason Miller wrote:

> I have a bunch of bristle nose plecos and am wondering how to sex
> them.  I notice that some have white tips at the corners of their 
> caudal fins, is this some sort of sexual dimorphism?  

No, it isn't.  Many bristlenose species have these white or cream tips at
the corners of their dorsal and caudal fins when young, and some species
have them even when full grown up.  I have never noticed any sexual
dimorphism in these spots.

> By the way, the males (assuming I have any out of ten fish) haven't
> got their bristles yet.  Most have tiny beginnings of bristles, but none
> have the elaborate bristles I have seen in older specimens.

The fisrt tiny spikes start to grow when the fish are about 5 cm - 2"
long.  Only males have any kind of beard on some species, and females have
some small stubs on other species.  And it depends on the species and
specimen how full beard there will be.  Sometimes just very short,
non-forked spikes, sometimes lots of branch-like bristles.  And it is
normal that only the strongest male grows a full beard, the rest have much
shorted bristles or no beard at all.

There are other ways to sex young bristlenoses too: wait until they are
sucking the front glass:  Males have wider heads and wider mouths.
Females have bigger bellies, less blunt noses and narrower mouths.  Males
have sturdier and more spiky first rays of pectoral fins.  That mouth
width is often easy to see even when the fish is just 3 cm long.  (Tomasz
Nidecki taught this to me when he visited me few years ago, thanks Tonid!)

> but since they eat algae,

The "common bristlenose" (temminckii- or dolichopterus-looking species) is
the best algae eater I have yet met!  They don't eat red algae, but most
types of green is eaten.  And they don't normally damage plants, even the
tasty swords, if vegetables and other food is given.  It is also one of
the easiest egglayers to breed and extremely hardy.