Hello,
It's pretty easy to tell Celebes halfbeaks,
Nomorhamphus spp., from wrestling ("Malayan") halfbeaks,
Dermogenys spp. Celebes halfbeaks are much larger (up to 11 cm vs. around 4 to 7 cm) and deeper bodied, giving the appearance of a sturdy, powerful fish. In contrast wrestling halfbeaks are rather spindly and delicate-looking. Some Celebes halfbeaks, such as
Nomorhamphus liemi liemi have crooked beaks, but not all of them. On the other hand, all the
Dermogenys have long, straight beaks.
I've been keeping these fish for about half a year, and as far as I can tell I have a mix of species including at least
Nomorhamphus liemi liemi and
Nomorhamphus ebrardtii. Other species of
Nomorhamphus almost certainly get imported under the "Celebes halfbeak" name from time to time. I'm currently raising a batch of 14 fry, about three weeks old now and growing fast.
What I can tell you about halfbeaks is this:
1.
Never, ever make a big water change. Every time I've done this, for good or bad reasons, I've lost one or more of the adults. Curiously, the fry seem much less sensitive to changes in water chemistry. But the adults are extremely intolerant of changes in water chemistry. A 5% water changes, once or twice a week, seems acceptable. I'm using rainwater which has a minimal ability to buffer changes in pH and hardness, so add a little hard tapwater and a sprinkle of sea salt as well. This seems to help.
2.
Water chemistry itself is irrelavant. These fish don't care about pH (mine have gone from over 7.5 down to almost 6 over the course of several weeks). Hardness isn't important either, except to say that moderate hardness is probably good because it buffers rapid pH changes. Salinity doesn't matter; you don't need to add salt for any of the freshwater halfbeaks, though arguably
Dermogenys spp. do better in very slightly brackish water, most probably because the salt is a good pH buffer as well. Mine have lived through filter maturation and high nitrates (up to 200 mg/l) so filtration isn't something to be overly bothered by.
3.
Breeding isn't a certainty. Even though these are livebearers, you can't expect them to be as easy to breed as guppies or mollies. The tricky bit is getting the female to carry the embryos to term; stillbirths are extremely common. I have twice found a stillborn halfbeak embryo in the tank, and presumably missed others that the catfish got to first. On the other hand, once the fish are born they seem astonishingly durable. Out of a brood of 14, all 14 have survived, even a few that went "walkabout" in the community tank for several days.
4.
The fry need live food and floating plants. Floating plants will keep them safe for (apparently) several days. They also help to make the fish secure. The fry swim on top of the floating plants, well hidden from other fish in the tank. The fry do not take dried food (whatever the books say) or Liquifry but will eat small pond animals, starting with things like cyclops and tiny daphnia. Newly hatched brine shrimps are too small for them. They do seem to eat frozen marine plankton and lobster eggs, though not as readily as live foods. My
Nomorhamphus fry were about 13 mm long when born, making them much larger that the average baby fish.
5.
They prefer live and frozen foods. One batch of halfbeaks I bought ate flakes, while the other didn't. All seem to relish live foods (such as mosquito larvae and brine shrimp). Frozen food is readily take as well, especially bloodworms. Proper feeding is supposedly a key to getting the fish to breed.
On my
web page there are some notes on halfbeaks as well as a "breeding diary" with photographs and charts showing the progression of the brood. Stop by and take a look.
These are really neat fish, and you'll have a lot of fun with them. The problem is that they are easy to kill if you do a big water change, and this is probably why they are considered 'problem' fish by many aquarists. Once you get past this, they're actually quite hardy and easy to keep.
Cheers,
Neale
A baby halfbeak, about 2 weeks old
