Sexing tailspot blenny (Escenius stigmatura)?

[therman]

Any pointers on distinguishing between the sexes in tailspot blennies?

I have had one for about a year and a half acquired as a small juvenile, which has grown and has a perpetually large belly...presume it is a female.

LFS currently has several of them in stock and I was wondering if there were any characters to look for that might indicate one is a male to pair her up.

Thanks,
Tim

 

[ThRoewer]

I'm not sure, but there is supposedly a fin difference like with Ecsenius bicolor. Bicolors have supposedly also a color difference. I'm currently trying to find out if this works with pairing bicolors.

Bicolor males have supposedly extended tail fin rays and are more orange while females have less orange and no extended fin rays.
I have two that are supposed to be male and female in a 10g QT and so far they haven't killed each other, though the supposed female is chasing the supposed male whenever she sees him.

One thing I found in scientific articles is that blennies do not change sex from female to male or the other way around like many other reef fish: when they are mature they are either male or female. So I don't know if their sex is predetermined at from the egg on or set at some later point.

The only sure thing I know to pick male and females on egg laying fish is the genital papilla. The female's is usually thicker than the male's. Checking them requires in many cases to slightly bend the fish to make it protrude (you got to find a store that allows you to "finger" their fish for this (or buy a lot and then return the cast-offs).

Here a few articles I found on this topic:
Sexing blennies using genital papilla morphology or ano-genital distance
Zur Biologie und Ethologie von Ecsenius bicolor

 

[therman]

Thanks! I saw the extended caudal fin rays on some in the store and wondered about that, since mine doesn't have them. Now I know what to look for in the future.

Much appreciated!

 

[ginpang]

Sexing tailspot blenny (Escenius stigmatura)?

I'm not sure, but there is supposedly a fin difference like with Ecsenius bicolor. Bicolors have supposedly also a color difference. I'm currently trying to find out if this works with pairing bicolors.



Bicolor males have supposedly extended tail fin rays and are more orange while females have less orange and no extended fin rays.

I have two that are supposed to be male and female in a 10g QT and so far they haven't killed each other, though the supposed female is chasing the supposed male whenever she sees him.



One thing I found in scientific articles is that blennies do not change sex from female to male or the other way around like many other reef fish: when they are mature they are either male or female. So I don't know if their sex is predetermined at from the egg on or set at some later point.



The only sure thing I know to pick male and females on egg laying fish is the genital papilla. The female's is usually thicker than the male's. Checking them requires in many cases to slightly bend the fish to make it protrude (you got to find a store that allows you to "finger" their fish for this (or buy a lot and then return the cast-offs).



Here a few articles I found on this topic:

Sexing blennies using genital papilla morphology or ano-genital distance

Zur Biologie und Ethologie von Ecsenius bicolor

Old post revival... The information on genital papilla is interesting but not super convenient on account that they're usually sitting on it...

About bicolor blennies , I've also tried this pairing method of one bigger with a lot of yellow with a smaller less colourful one. At first it was total chaos , I wanted to catch either one and give it to a friend or bring it back to the store. And then the smaller one got a really good hiding place with a back doors exit... I put in more possible hiding places until I was able to catch one.. Because I was worried for the little one who's super shy and rarely comes out.

Then I noticed the bigger one going from his regular hole to closer hideouts to the other one and basically " polices" the area . Sometimes even pops in to the other one's back doors and exits through the front entrance. At first I was sure they two males. Now I'm confused , could courtship be somewhat aggressive if the " female isn't quite ready?" Or vice versa seeing that your " female" chases the male around.




I also remember reading on another forum discussion that dates a few year back on someone trying to pair them and with five specimens this person claims the only positive ID on a female was a slightly smaller Blenny with just as much yellow as the others but had yellow or ( see-through) tail fin Rays . As for the other four had dark almost black tail fin Rays . Both sexes had " streamers".

The other thing I wonder about and that no one talks about is the black dot behind the head on the dorsal fin. Could that be gender related ? Or is that just a regional difference in populations?! Could it also just be a regular coloration for a " mature specimen" as opposed to a juvenile?

 

[ThRoewer]

Well, unfortunately the genitals are to my knowledge the only reliable distinguishing feature with this genus. With Ecsenius I wouldn't trust coloring at all. I had once a nicely black and orange colored single bicolor blenny that one day layed eggs on the front glass.

Other blennies can have vastly different sexes, not just in color but also morphology.
In the Mediterranean I caught once a bunch of blennies and brought them back home. There where some very colorful and some more simple colored that also had a vastly different morphology. I was sure those were different species.
But only a few days after I had put them into their new home I found the prettier one in a cave watching over a bunch of eggs. Turns out, they were just male and female of the same species.
As a result of such sexual dimorphism it is also highly possible, that for several species only the prettier males get collected while the more plain colored females get ignored.

Unfortunately Ecsenius are not that easy to sex.

Blue Zoo Aquatics offers male and female Ecsenius bicolor and I gave it a shot. Though, unfortunately the "female" killed the "male" while in quarantine. By now she almost completely black.
I just got another "male" that is now in quarantine. When he is done with that I will have a closer look at both under my microscope to see if there is the difference that should be there.

 

[ginpang]

Sexing tailspot blenny (Escenius stigmatura)?

Very interesting let us know how it turns out ...

In the last 48 hours my larger " male " who was the aggressor is now hard at work spitting out rocks from the " back entrance" of the other one's hideout. He's acting exactly like was my pearly jawfish and stonogobiops were acting when digging a burrow for their " family" .
Anytime in the past 17 years in the hobby that I had a bicolor it always perched high up where it could see everything going on. I had never had one make a burrow half in a live rock half under gravel!
I always surely had some luck involved putting 2 fish together to pair up... Yet after 3 weeks I still don't know what's happening , the little one still appears to be terrified to come out and yet the other one is super involved around that burrow?!
I'll be sure to put up any developments if there are any.

Thanks