One of our readers asks about the difficulty of breeding Celebes halfbeaks and Neale is on hand to answer.
I have six Celebes halfbeaks (Nomorhamphus liemi) – two males and four females – in a 90x38x38cm (36x15x15”) aquarium. I feed lots of live and frozen foods and the tank is full of live plants.
The tank also contains corydoras catfish, a bristlenose and a large group of harlequin rasboras. I've had the halfbeaks about six months, but I've never seen any livebearer fry – in fact the females have never even looked pregnant. Are they difficult to breed or am I doing something wrong?
SARAH BISHOP
Neale outlines why breeding halfbeaks can be difficult
Halfbeaks are certainly breed-able, but they are much more difficult than their livebearer status might imply. In fact, there are any number of egg layers that are far easier to spawn and rear. This includes the corydoras catfish that are also in your aquarium.
Precisely why this is, is hard to explain. In theory, breeding should be straightforward.
They’re obviously sexually dimorphic, so making sure you have both males and females is easy enough. Males have more intense colouration, an andropodium and can display a hook shape to their lower jaw.
Female top, male bottom, All photos by Shutterstock
Water chemistry might be a factor, but Celebes halfbeaks aren’t especially demanding in that regard. So long as your water isn’t too hard or too soft, and has a roughly neutral pH, you should be good. I kept and bred mine in a 50:50 mix of rainwater and tap water – something like 10°H, pH7.5. On the other hand, they don’t appreciate high water temperatures, with 22-24°C (72-75°F) suiting them well.
Related article: What conditions do halfbeaks need?
Is diet key when breeding these livebearers?
So, why don’t they breed as freely as guppies or mollies? Well, one problem might be diet.
Your classic Central American livebearer is fundamentally an omnivore. They happily consume algae, decaying plant material, and small invertebrates like insect larvae. They all scrape away at rocks and plants and then consume whatever edible matter they find.
Therefore, replicating the diet of a Central American livebearer is relatively easy. Indeed, the food we give them is probably far more nutritious than anything they’d get in the wild.
Halfbeaks are much more carnivorous and specialise on feeding on insects that fall onto the surface of the water. Some may also consume zooplankton and even pollen as well but this is a much smaller part of their natural diet. Being such specialised feeders, it is possible that we are missing something key in their captive diets. Meaning that they do not get into breeding condition as quickly in aquariums.
Related article: Frequently asked questions on livebearers.
Halfbeak cannibalism
On top of that, these fish are prone to consuming their fry. In the wild, newborn fry likely swim into dense rafts of vegetation or shallow water where the adults don’t go. Because of that, the adults are unable to discriminate between a baby halfbeak and nice juicy insect larva. Therefore, the parents are likely to hunt down any fry they come across in your fish tank long before you see them.
Adding plenty of floating plants will help, with Ceratophyllum demersum working well for me. Floating plants will also inhibit the tendency of adult halfbeaks to throw themselves around the tank when alarmed. Check the plants regularly and remove any fry to another tank. Even a floating breeding trap will do if you need time to set up a rearing tank.
Juvenile halfbeaks stay close to the surface
Help your halfbeaks settle by providing a calm environment. Offer a varied diet that includes plenty of small insects like wingless fruit flies. They are greedy fish that respond best to frequent, rather than large, meals. If you feed your fish once or twice a day – which is fine for most community aquariums – consider offering smaller meals 4-5 times instead.
Interesting facts about Celebes halfbeaks
The Central American livebearers naturally inhabit ponds, ditches, and other sorts of shallow, often rather oxygen-poor environments. Celebes halfbeaks, on the other hand, swim in more open areas with steady currents and plenty of oxygen.
Halfbeaks do best in well filtered tanks with excellent water quality. They also struggle to adapt to life in the confines of the aquarium. They’re skittish, which makes sense in the wild where predators can come at them from all angles.
In that context, leaping blindly is one way to avoid predation. However, in an aquarium that can often mean they damage themselves when alarmed. Even if they don’t damage themselves externally, shock can cause miscarriages in pregnant females. Equally, they are likely to leap out of open topped aquariums, so always use a tight fitting lid.
Not all halfbeaks are livebearing species giving birth to live young. For example, Hemirhampodon tengah, a stunning small fish from borneo, lay eggs in dense aquatic plants.