What is this organ?

[aotoo]

I know the male have gonopodium, but I noticed the female also have something under the vent.
As far as I know, Hoplosternum littorale and Callichthys Callichthys female have it.
What is this?

[bekateen]

Your first photo looks a lot like a fish louse. In your second photo, what are the white lines by the anus? Are those worms?

I hope I'm wrong on both.

Good luck,
Eric

[Kirin]

I agree looks like a fish lice. I see these occasionally on SA fishes and I always called them fast fish lice as they seemed to move over the fish particularly if being caught. So now I'm not sure if they are another isopod particularly those that burrow into the fish. Generally if it looks like a louse I'd quickly check over the fish.

[aotoo]

Thank you for your help.
But it isn’t fish lice or something.It is definitely part of the body.I know male’s white one is gonopodium and I personally think female’s transparent one is ovipositor.

[bekateen]

Hoplos don't have a gonopodium. That doesn't look healthy to me.

Regards,
Eric

[bathyclarias]

"Gonopodium" in fishes more narrowly refers to a modification of the male anal fin used to inseminate females.
In this case, both the male and female structures would just be called genital papillae. In the females, I don't think it has any known function as the eggs are expelled from the urogenital pore.
Also it seems this is not the first time the genital papillae of callichthyids has been mistaken for parasites:
https://www.planetcatfish.com/forum/vie ... hp?t=35290

[bekateen]

"Gonopodium" in fishes more narrowly refers to a modification of the male anal fin used to inseminate females.
In this case, both the male and female structures would just be called genital papillae. In the females, I don't think it has any known function as the eggs are expelled from the urogenital pore.
Also it seems this is not the first time the genital papillae of callichthyids has been mistaken for parasites:
https://www.planetcatfish.com/forum/vie ... hp?t=35290

Thanks for sharing. I've never seen them before on Callichthyidae and didn't observe them in photos of H. littorale.

It's a shame the link inside that thread is dead and the images are gone.
I'd Like to see it in other photos.
Cheers, Eric

[bathyclarias]

Indeed, considering how prominent the organs are, I'm surprised there aren't more photos on the web.
There is a good one for Megalechis: https://www.scotcat.com/callichthyidae/ ... acata8.htm

[bekateen]

Indeed, considering how prominent the organs are, I'm surprised there aren't more photos on the web.
There is a good one for Megalechis: https://www.scotcat.com/callichthyidae/ ... acata8.htm

Thanks!

[Jools]

You can see it here too on one of my old males:

https://www.planetcatfish.com/common/im ... ge_id=1520

These guys (I think the bubblenesters) both male and female have longer than you'd expect genital papillae which I think is to do with the whole swimming upside down and laying eggs thing.

Cheers,

Jools

[bekateen]

You can see it here too on one of my old males:

https://www.planetcatfish.com/common/im ... ge_id=1520

These guys (I think the bubblenesters) both male and female have longer than you'd expect genital papillae which I think is to do with the whole swimming upside down and laying eggs thing.

Cheers,

Jools

Thanks Jools. That photo also gives an appearance like that in the OP of what I interpreted as a louse. This makes more sense now.

Cheers, Eric