They’re odd looking, fragile and like to wrestle each other. But Gabor Horvath says they’re well worth the effort.
Distinctly odd-looking, slender Wrestling halfbeaks are highly recommended if you want to keep (and breed) something just a little bit different.
There are beautiful fish and even more beautiful fish. There’s no such a thing as an ugly fish – I prefer to call them odd.
The halfbeak family, hemiramphidae, got more than its fair share of oddity, with overgrown lower jaws and rugged heads – just take a closer look at them. Most of the halfbeaks are marine species, but there are a few interesting livebearer ones that spend their lives in freshwater or brackish-water environments.
The halfbeaks available in the market share many similarities, but there are still some significant differences between them that you need to consider if you want to keep and breed them successfully.
The freshwater halfbeaks most frequently sold in the UK belong to the genera Dermogenys and
Nomorhamphus, and here we’ll be looking at the former of those.
These slender pike-like fish had been on my aquarist bucket list for ages, but for some reason I couldn’t get hold of any. Then my luck changed and I spotted a nice group of Wrestling halfbeaks at the JMC aquatics’ stand at the aqua Telford show. Fortunately they let me have 10 of them (thank you, Jane!) and I could begin my halfbeak project.
I’ve learned a lot about these interesting and very loveable fish in the past few months, so now it’s time to share this knowledge.
The genus Dermogenys includes several species, such as D. pusilla,
D. sumatrana and D. siamensis. The smallest and the least colourful of the trio is Dermogenys siamensis, barely reaching 4cm in length. In the other two species, the females can grow up to 7cm while the males stay a little smaller, peaking at 5cm.
Colour-wise, the two larger species are quite similar, with the
males sporting orange or reddish dorsal and anal fins. The easiest way to tell them apart is based on the position of the ventral fins. In the case of the true Wrestling halfbeak,
Dermogenys pusilla, they’re positioned around midway between the pelvic and the anal fin, while
Dermogenys sumatrana has them closer to the anal fin.
Wrestling halfbeaks can vary greatly in body colour, from the ‘natural’ silvery brown, through to gold, and to the almost white ‘platinum’ variety. All three
Dermogenys species mentioned make appearances from time to time in the shops, and all are traded under the collective name of Wrestling halfbeak.
The ‘wrestling’ moniker originates from the males’ keenness to get involved in territorial disputes with their rivals – a behaviour that’s especially prominent in wild-caught fish. Those long beaks serve a purpose – to decide who’s boss they grab each other’s beak and try to wrestle down their opponents. These fights can sometimes last over an hour, especially in the confined spaces of aquaria.
In the fishes’ countries of origin, people use them for fish-fights, with bets placed on the outcomes, just as happens elsewhere with Siamese fighting fish. In aquaria this fighting spirit is unwanted, but with clever positioning of tank
Halfbeaks are very interesting and challenging fish to keep and breed. I can strongly recommend them to those wanting something different
decor we can significantly reduce fight frequency by breaking up lines of sight and dividing the tank into distinct territories.
My fish are fortunately quite docile, as they were probably tank-bred, so most of the time their sparring only goes as far as a bit of fin-flaring and mouth-gaping. Sometimes the females also join in the territorial disputes, but those don’t last for long. The plentiful floating plants (Salvinia) in my tank definitely help to reduce aggression, as they break up the lines of sight and also offer a retreat for the weaker fish.
Making a home
The natural habitats of the
Dermogenys halfbeaks include slow-moving rivers and still waters in South-east Asia. Most of these biotopes have dense vegetation, with floating plants or submerged plants reaching up to the surface. Halfbeaks spend most of their time among this surface greenery, waiting for an occasional insect to fall in. Their elongated lower jaw and up-facing mouth enables them to quickly pluck the unfortunate fly from the surface. To keep them in peak condition we should provide them with a similar environment and diet in the fish tank. As Halfbeaks, especially those belonging to the Dermogenys genus, tend to stay near the top, the amount of surface area is much more important than the height of the aquarium. A fish tank with a 90x45cm base and a tight-fitting cover is perfect to house a small group of them. They’re very adaptable and can be kept in a range of water conditions, so long as the extremes are avoided and the water quality is pristine. Fill up their tank with water around 23-26°C, with a hardness of 5-15° and keep it close to neutral – 6.5-7.5ph – and you should have no problems. Keep the parameters steady, as these fish can be sensitive
to sudden changes in both acidity and temperature.
Sometimes, halfbeaks can be found in brackish habitats in the wild, and to mimic this some aquarists put a little aquarium salt into their water. It’s not essential though, and every species discussed here will happily live and breed in completely freshwater tanks at the parameters listed above as well.
Decoration-wise, they’re not very fussy. Basically, they don’t care about anything below their eye level. When choosing decor avoid hard rocks and other similar blunt objects, which could damage their beaks.
Beak injuries are quite frequent, as halfbeaks are easily spooked. When startled, they dart around the tank like tiny missiles, hitting the glass or jumping out of the water altogether. So for the first few days after their arrival, be very careful when approaching their tank.
Use lots of floating plants or other vegetation reaching the surface to help relieve this initial stress. Dense floating vegetation also helps if you want to breed them, as it provides protection for the newborn fry.
Persevere and in time your fish will learn that your appearance means food and they’ll become braver. My Wrestling halfbeaks are always the first to get to the food now, frequently poking my fingers with their beaks to release their favourite treat of bloodworm.
Feeding and tankmates
Halfbeaks are not very picky eaters, as in nature they would grab anything edible falling into the water, be that a worm, insect or plant. If you imitate this natural variety by feeding a range of frozen meals – bloodworm, Artemia or DIY frozen food – as well as flakes, floating granules and live foods such as Daphnia, mosquito larvae and fruitfly, they will be eternally grateful. The only thing to remember is that if the food sinks further than 15cm or so from the surface, the halfbeaks will rarely bother to follow it. To avoid water pollution, it’s a good idea to keep some cleaning crew with them to pick up these falling morsels. Despite the pike-like, predatory appearance of halfbeaks they’re generally peaceful and can be kept well together with similarly sized community fish. Avoid boisterous fish as tankmates, as halfbeaks won’t withstand even light harrassment. Also avoid excessively small fish (like Boraras microrasbora), because they may be considered as dinner.
I house my halfbeaks with Peacock gobies, Tateurndina ocellicauda, and it’s a match made in heaven – the halfbeaks always stay near to the surface, while the gobies occupy the lower regions, breeding away.
Corydoras catfish, mollies, platies, small rainbowfish and deep-bodied tetras are all suitable tankmates.
Dermogenys halfbeaks are livebearers, but probably the hardest of the halfbeaks to breed. Even when successfully bred, the brood is quite small, consisting of only six to 20 youngsters after a 26-42 day gestation period, dependent on temperature.
The difficulty isn’t getting them pregnant, as mature males make constant use of their andropodium – a modified fin-ray used as a reproductive organ, much like those of guppies – to ensure progeny.
The problem is that females will give birth prematurely if frightened, or produce stillborn fry despite
being given the best possible care.
One reason often given for this is the lack of certain vitamins in the adults’ diet. I’ve always tried my best to provide my fish with rich food, which included regular portions of black mosquito larvae from my water butt. Nevertheless, I was still a bit nervous when I saw two of my females getting progressively plumper, which is a sure sign of an ongoing pregnancy.
I’d read contrasting reports about adults preying on their fry, so to ensure the survival of the offspring, I moved one of the females to a well-planted separation tank when I thought the time was right, and divided my breeding aquarium into two with a hard plastic mesh to protect the newborns.
I must have guessed the timing right, as next morning I found eight tiny silver ‘splinters’ hiding among the vegetation. Compared to the fry of common livebearer types like platies, these were quite large at around 6-8mm long. This meant feeding them caused no problem at all, as they accepted newly hatched
Artemia and powdered floating flakes straight away.
Interestingly the newborn fry of the halfbeaks have no beaks yet – they just look like a ‘normal’ fish. It takes a few weeks before they begin to fully resemble their parents.
Since my first success I’ve had several broods, the largest consisting of 14 fry. Luckily I didn’t experience any of the pregnancy issues, probably due to the extra care taken around water changes and a varied diet.
The latter is a key factor to success. I did a small experiment to see the effect of feeding on the development of the juveniles. I divided one lot of fry into two, feeding the first group with high-quality dry food only, and the second with a variety of live and frozen fare. Among the members of the first group, half of the fish became somehow deformed and even the rest remained much smaller than the ‘lucky’ fry in the second group. They obviously wouldn’t make ideal breeding stock.
Wrestling halfbeaks are interesting and challenging fish to keep and breed. I can strongly recommend them to those wanting something a little different. If you’re prepared to go the extra mile and treat them well, I’m sure these happy halfbeaks will give you a smile.
The ‘natural’ silvery brown male (below) and female (above).
Bloodworm is a favourite food.
BELOW: You can see where the beak will develop from in the fry.
ABOVE: Fry look suprisingly normal, not even quarterbeak.
BELOW: Less striking, but the natural strain is more colourful.