Elephant nose - looking for breeding info

[Plums]

Hello all, I'm new to this forum but it all looks very good.

I'm looking for information on breeding peters' elephantnose fish (Gnathonemus petersii). I know they are difficult to even keep in groups nevermind breed but I've read that it has been done in captivity. I think they've been bred by water companies and also for research. There's apparently also a breeding account in "Het Aquarium", a dutch fishkeeping magazine, but I've not been able to get hold of it.

So if anyone knows anything about breeding these guys I'd be very grateful.

Any info on sexing them would be helpful too. There's a subtle difference in the anal fin between male and female but the description of it I have is very vague.

I've had my EN for a year now. I'm not planning on trying to breed just yet but maybe sometime in the future.

This might be a bit of a longshot. Oh well, Thanks.

[fishboy]

what size tank you got it in?

[Plums]

s/he's in a 34 gal (US) at the moment, sharing with some white cloud minows.

[DUSTIN323]

I've only read that they can't be bred in captivity not to say that they couldn't but I'm sure it would be hard.

[TheOldSalt]

Well, it is hard. Very hard.
This fish has a few peculiarities which make spawning it freakishly difficult.

The easiest way to sex them is to hook up a sensor to measure their electric fields. That's how they tell themselves apart!
That's also the problem:
in captivity, the male/female sex frequencies get scrambled. It becomes very hard for the fish to tell each other apart, and spawning becomes almost impossible. This can be corrected however in a HUGE tank with very correct water chemistry that doesn't interfere with their fields. The males also have an indentation in their bellies where their anal fins attach. The first few rays of the anal fin are also thicker on the males.
Spawning itself involves a belly-to-belly kind of thing during which the anal fins are erected to form a little spawning pouch where the bellies sink in as a result.

i guess you could try google for a lot of other info, but you'll probably have to sift through a lot of stuff to get what you need.

[Plums]

Many thanks for the help. The more I've looked into this the more it's become a bit of a pipedream, it's still interesting but not very likely to happen.

I didn't know about the indentation that males have. From what I've read, they can be sexed by cutting them up with a knife, which is a little drastic, by their EODs (electric organ discharges), and by their anal fins. Radiography is also mentioned quite a bit, which I'm guessing is a bit like xrays and lets you look inside the fish.

This is what I had about the anal fins - "Adult and subadult males show bone expansion at the base of a select number of anal fin rays (Brown et al., 1996; pezzanite and Moller, 1998); this characteristic is lacking in females."
from - http://biology.uky.edu/Yan/N0.%2012,...ion_social%20i

I can't tell anything about the anal fins looking at the one I have.

I googled around and found this - "Males were identified by the distinct indentation at the dorsal margin of the anal fin."
from - http://www.anovascience.com/pdf%20fi...ivityModel.pdf

So there's your indentation. My EN does seem to have a small notch there compared to, well, almost all of the elephant nose pictures I've seen.

The article in that last link also shows a big problem like you said. The ENs in the wild use their electric fields to tell each other what sex they are and who's ready to mate etc. The study seems to show that this all falls down when they are brought into captivity which seems to stop them signalling what sex they are, and can even make males signal like females and females signal like males.

I haven't given up just yet though If anyone has any thoughts/further information please let me know.

When I have some time I'll put together everything I can about breeding these guys.

Btw. OldSalt, how did you get to find out about the anal fins/indentations?

[TheOldSalt]

I don't know...it's just one of those things I picked up somewhere along the line.