Re: Very Sick Black Molly... (RMF? Ever seen this type of prolapsed vent on a Molly?) Nomorhamphus liemi  7/8/09 Hi Bob, <Neale> Images attached. Includes alternative version with the prolapsed vent highlighted and labeled. These are gratis for your use on WWM where relevant. Cheers, Neale Re: Very Sick Black Molly... (RMF? Ever seen this type of prolapsed vent on a Molly?) 7/8/09 Hi Bob, Have sent the images along. <Have seen. Thank you Neale> For what it's worth, in the case of this halfbeak, by guess is that  hybridisation might be the culprit. Within the genus Nomorhamphus, there's a spectrum of degrees of viviparity, from simply ovoviviparity through egg/embryo cannibalism to proper placental connections. Since they're all a closely related species flock from a single island, I wonder if closely related species can fertilise one another, but as  the embryos develop various failing develop if the connection with the mother isn't "just so"? <Possibly> It's a shame exporters make no effort at all to offer a single species in each batch of fish, and this may further explain the supposed difficulty of breeding halfbeaks in captivity. Cheers, Neale <Such is both the nature of the trade presently, and the broader nature of humans... We are "fighting" this gradient... Cheers, BobF>

Halfbeak care and purchasing  12/16/08
Hi all!
Great website! I've been doing lots of reading here. I currently have a slightly brackish, planted 29 gallon tank with platies, mollies, and a Krib. I was at a local pet store today that sometimes gets a few oddballs and they had one lone halfbeak. It was labeled as a "Celebes Halfbeak" but it looks almost exactly like this picture:
http://www.aqua-fish.net/show.php?h=halfbeak1
<That fish appears to be the so-called Silver or Platinum Halfbeak, a species I believe to be Dermogenys siamensis. The Celebes Halfbeak is Nomorhamphus liemi. You can easily distinguish Dermogenys from Nomorhamphus. For a start, Dermogenys halfbeaks are generally smaller and more slender in build. Dermogenys halfbeaks also have longer "beaks". When viewed from above, Dermogenys halfbeaks have semi-transparent "flanges" on either side of the lower jaw, so that there's a scoop-like construction that is presumably used to guide food particles into the mouth.
Nomorhamphus halfbeaks lack these flanges, and generally have short, stubby beaks that curl downwards in some species. Nomorhamphus have a stocky body shape, and the females especially are very sturdy-looking. Nomorhamphus also seem to be happier swimming at different levels of the aquarium, even the bottom, whereas Dermogenys rarely go much below the top of the tank.>
Straight beak, silver body, red and yellow fins. It's a little over two inches, and the lady who does the fish ordering says she's never seen any with a hooked beak like the actual male Celebese, but yet has seen them breed in the tank. Supposedly he's been eating flakes. I decided to take the little guy home and see how he does. She'll be ordering a few more soon, as well as the flag fish I was hoping to find.
<Does sound like Dermogenys siamensis. I have a picture of a male and female on one of my web pages, here:
http://homepage.mac.com/nmonks/Projects/halfbeaks.html
Scroll about halfway down.>
Are there other species that look close to this picture that I should also consider? He's currently loving my thick stand of hornwort so I don't know if I'll be able to get a picture soon.
<Yes, they do like floating plants!>
What exactly does the andropodium look like? I can't find any pictures on Google and it sounds like it's not as well defined as the gonopodiums of my other livebearers.
<Correct; essentially all you will see is that some of the rays in the anal fin are kinked. But don't expect to see anything like the gonopodium of a male livebearer. Regardless, they're quite easy to sex once you compare males and females in the same tank.>
I'd like increase my single fish into a properly sexed trio if possible.
Or would that require more space than my 29 gallon? Some articles say they're aggressive with each other.
<Dermogenys are aggressive, but in your tank I'd get half a dozen and let them sort themselves out. They won't fight to the death if there are plenty of floating plants.>
Also, my current feeding regiment includes Spirulina flakes, a color boosting tropical flake, peas, and frozen bloodworms (and livebearer fry, which everyone seems to relish!). Will this be a sufficient diet for the halfbeak, or should I look at adding something else?
<Sounds perfect. Algae-based flake is probably essential, as halfbeaks are at least partially herbivorous in the wild. My specimens thoroughly enjoy Hikari Micro Pellets as well.>
Also, I'm getting conflicting information on water changes. I currently do weekly 30% water changes. One of the articles recommended changing only 5% at a time. Are halfbeaks really that sensitive or will my current weekly schedule be suitable? I do check the parameters every day or two just in case. Both my tap water and my tank water are pH 7.5 so there wouldn't be a pH change.
<Some halfbeaks are sensitive to water chemistry changes, particularly Nomorhamphus. But Dermogenys are generally quite tough, and some species occur across a wide range of water chemistry values. Dermogenys pusilla for example can be found in fresh, brackish and saltwater conditions. Provided you don't expose your fish to extreme, rapid water chemistry changes, they should be fine with the usual 30% water changes you do.>
Thanks!
Angela
<Cheers, Neale.>