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I have two Hypancistrus sp. L-260 "Queen arabesque". One of them is 5-6 cm and the other one is apx. 8 cm long. Today, I noticed that both of them had a "mustache" sticking out of their interoperculum (thats what it's called right?). The upper "hairs" where longer than the lower ones.

It looked much like the ones on thsi L-66 (the middle pciture)
http://www.planetcatfish.com/icosa/lect ... inae03.htm

Does this mean that i have got two males, or is this normal for both genders?

Hi!

Well I don't like using much the interopercular odontodes growth on Hypancistrus at least has, such features is present on both male and female.
On dominant male, these are pretty long and furnish, so not much of a doubt concerning the sex of this one
On female, rather short and not as much furnish than those of the dominant male.
That stuff get tricky when dealing with a submissive male, on him it is most likely to look like what the female has, rather short on not as furnish than the dominant male, but still just a bit more than what you will find on the female.

You should check the odontodes on the hard ray of the pectoral fins, there is no differences between submissive and dominant male there. They are long and well furnish, and rather pretty short and more spaced in female

Hypancistrus spp males also develop odontodes on the plate of the body and also on the hard ray of the other fins, these are rather short, it is clearly visible on big specimen but is pretty difficult to see on rather small species such as Hypancistrus zebra, female do not develop such feature at all

Such features can only be seen in well establish fish , that had been kept for a long time together in the same tank, and not on newly imported fish or newly introduce in a tank.
It is also rather impossible to sex 100% correctly immature fish.

At 8 cm you should be able to sex him, but at 5-6 cm, it is still a bit to early to tell.

Finally I have read some where the L260 males have a marbeled stomach and female doesn't, I doubt it is a sexual dimorphism that work all the time, but so far it has for me, all the fish of that species that I have seen exhibited such feature!!!

Cheers
Yann

If this thing about marbled bellies is true, i have got two males.

I took a closer look at the biggest one today, the mustache seems to be around 1 cm long.

What is this hard ray you mention?

hi!

The hard ray is the part the is well in the front of the fin that the fish can lock iin case of danger...
Cheers
Yann

Could you post a picture to show the difference between the marbled and normal bellies?................................................................................ ................................................................................

Hi

Here is a pic of a believed male L260, picture taken from http://cichlidae.netliberte.org

http://cichlidae.netliberte.org/loricar ... 60male.jpg
Cheers
Yann

That's just how my two L-260's look on their bellies. I would love to hear other peoples experiences with this fish and if the decorations of the bellie allways means it's a male. It would be great to have such an easy way of telling the genders apart.

I have 9 of them and I have never look if there is any different in the bellys between female and males and they have spawned twice last year. I know I have at least three males and three females of them but everyone is in the same tank and have just started to spawn again, after this season I will take a closer look at them and see if it's in that way...that the females does'nt have any spots on the belly.
Can it be so easy to sex them...

Janne

hehe Janne, I was thinking the same thing! I have 8 of them in a tank with rockwork, caves, and driftwood. I put them in there to quarantine, and 3 months later, they're still there. I haven't seen any fry, and I was considering moving a pair into a smaller tank by themselves. I haven't attempted to actively sex them all and count how many I have of each. I know I've seen two that were visibly male by the look of their fin ray and odontodes, and 3 that are definitely looking more female, but sexing them with that method will make my life much simpler Thanks Yann!

Barbie

Hi!

You are welcome ,it is a real pleasure... still the male pictured there show really well marbeling in the ventral region, but i have seen many male having just a bit of marbel in the ventral, with far more white than marbel, still they were male, female that I have seen were totally immaculted white in that region!
Inmature specimen look like female!!!
Cheers
Yann

All of mine are well over 3.5 inches, and 2 of the males are closer to 5 tl, so I'll definitely be working on sexing and separating fish this weekend. Have you had better luck spawning them as a colony? Or paired into individual tanks? My albino bristlenose seem to spawn like mad no matter how I keep them, but a friend of mine had much better success with his qa's in a pair only tank. Thanks for any light you can shed on the subject

Barbie

Hi!

Well I keep my fish in group with several female and male of each species...

Each time only the dominant male did spawn, somhow the submissive male does not look attractive enough for the other females!

Cheers
Yann