A Data to Caring for the Borneo Redline Halfbeak
Phrases by Alex Bell
Like many aquarists, my publicity to halfbeaks has been restricted to just a few encounters, and all of those have been with just one species: the wrestling halfbeak, Dermogenys pusilla. Followers of this species will understand it as a fish that’s extraordinarily tolerant of water chemistry, from stagnant freshwater ditches to flooded brackish mangroves. Although nonetheless very loads on the bizarre side, I had not lower than seen them in just some retailers and one buddy’s aquarium.
As superior as this species is, that is as loads as I’ll write about it at current. In its place, my focus is on a fish barely further suited to my conventional water chemistry, and positively a fish a lot much less often seen.
A family peculiarity
I began planning a model new tank almost half a 12 months sooner than I’d really get it filled with water. This gave me far an extreme period of time to dive into rabbit holes on-line, researching utterly totally different habitats to encourage myself. My requirements have been straightforward: to utilise botanicals and reside vegetation collectively to provide one factor aesthetically pleasing, nonetheless that combination moreover wanted to function like one factor in nature.
Whereas researching Borneo biotopes, the place Cryptocorynes and Bucephalandra develop wild and leaf litter dominates, I discovered that there have been further species of halfbeaks than I ever knew existed. Furthermore, the complete species located throughout the three genera (Hemirhamphodon, Dermogenysand Nomorhamphus), found contained in the family Zenarchopteridaeare viviparous. In viviparous fish, or livebearers as many individuals will know them, embryos develop inside the female and completely formed fry are birthed (much like the livebearers in Poeciliidae—the guppies, platies, mollies, and additional). Nonetheless there’s one exception— the Borneo redline halfbeak (central Hemirhamphodon).
No matter Borneo Redline Halfbeak (H. tenach) not giving begin to reside youthful, it has been seen that the eggs laid by the females are already fertilised when launched. The stage of progress on the extent of launch stays to be unknown as no consistency to the eggs collected have been recorded.
Apparently, it’s often thought that the sperm transferred to the female all through copulation is not immediately used for fertilisation, with the female starting to swell with eggs many days after the event—which could contribute to why there isn’t a such factor as a consistency to the stage of the eggs upon launched.
A analysis analysing the distribution of life historic previous traits inside Zenarchopteridae implies that the viviparity prevalent all through the three genera comes from one frequent ancestor. However an obligatory question stays unanswered. Has H. middle managed to retain a primitive trait whereas evolving alongside the rest of the genus, or has the species developed once more from reside bearing to oviparity?
In my fairly uneducated opinion, it is further probably that each of the three genera diverged from the shared ancestor, sooner than the descendants of this ancestor break up into the species that we see at current. This seems significantly further plausible than H. middle splitting off sooner than evolving viviparity, however creating the similar traits as the rest of the Hemirhamphodon spp. Each method, the benefits for this one species to not carry their eggs in the midst of incubation, and the environmental pressures which may have launched it about, keep unclear.
Small fish, big space
No matter their small most dimension of 5cm, H. middle do significantly better in aquariums with a giant footprint (or perhaps ‘surface-print’). All halfbeaks are obligate ground dwellers, not typically dropping extra than just some inches from the very best of their tank. Throughout the wild, to enterprise away from the sanctity of any floating or marginal vegetation is to be merely picked off by predators, be they birds from above or larger fish beneath.
As such, they’ve developed to dart away swiftly at any time when there is a disturbance shut by; throughout the wild this takes them from quick hazard and (hopefully) into areas with some cowl. In aquariums, this luxury of space is denied to them and they also encounter a giant sheet of glass, and after they do this the repeated collisions will hurt the delicate, elongated lower jaw.
I maintain a gaggle in an aquarium with base dimensions of 100x40cm nonetheless they spent some time in a 60x30cm quarantine tank and thru this time I seen fairly a couple of collisions with the tank’s sides. Nonetheless, I’d take into consideration a tank dimension between the two might very nicely be acceptable.
If maintained in a restricted space, there are strategies to reduce the hazard of collisions. Firstly, by planting tall, shade tolerant vegetation like Cryptocoryne balansae throughout the once more and sides of aquarium. These will, often, current safe areas for the fish to flee to easily sooner than they collide with glass. The presence of planting will reduce the conditions of preliminary darting too, as a result of the fish will actually really feel a lot much less nervous when nestled between the fronds. Alternatively, chances are you’ll paint the once more and sides of the aquarium black, which might present a visually perceptible barrier, and one the fish are ready to tell apart further merely than clear glass.
This skittish nature moreover means they’re susceptible to launching themselves out of the aquarium, and so as with so many nervous species, an excellent lid or cowl glass is certainly required.
Combine a tight-fitting lid with a ground rich in floating vegetation to help the fish actually really feel safer, and the place attainable (and the place experience permits) utilise a daybreak/sunset function to the lighting allowing it to ramp up and down usually at morning and night time. Sudden and shocking publicity to stark illumination or darkness is probably going one of many key stressors in making fish bounce and dart.
Current the creature comforts
As always when considering a model new species, you may need to affirm if you happen to occur to can current the correct water chemistry for them. Dwelling throughout the peat swamps of Borneo, it is a safe assumption {{that a}} clean, acidic environment may be needed. A pH beneath 6.5 will most likely be acceptable nonetheless for a lot of aquarists which implies utilizing reverse osmosis water will most likely be required—this may increasingly additionally maintain the carbonate hardness low which is usually a necessity.
H. middle is strictly a tropical species, so temperatures between 25-28°C must be maintained all 12 months lengthy with out the need to imitate big scale seasonal variation.
Feeding isn’t as powerful as usually reported; if it floats, they might not lower than try it. Flakes, granules, frozen and reside meals are all accepted, with white mosquito larvae being an excellent different as even the defrosted larvae will float on the ground. As shortly as a result of the meals drops beneath just some inches from the water ground the halfbeaks will ignore it.
For tankmates (if any) you want comparatively timid-feeding species, as any ground disturbance from ravenous larger fish might trigger big proportions of the meals to sink. In such a setting, you’ll shortly uncover that the halfbeaks will wrestle to get enough meals if they are not significantly settled and guaranteed.
On the totally different extreme, smaller fish may be susceptible to being snapped up by the halfbeaks themselves, with diminutive ground dwellers notably in peril. So, there are already some restrictions on potential tankmates sooner than we even bear in mind their should moreover thrive in clean, acidic conditions.
An excellent selection for such a definite phase species is to take a look at what’s biotope applicable. Fortuitously, many engaging fish moreover identify these swamps dwelling and make good companions. Species of the genera Parosphromenus, Sphaerichtys are calm additions, however big enough to avoid turning into dinner. The Boraras spp. shall be considered nonetheless assure they’re big and mature folks as a result of the small ones, merely after being imported, might very nicely be in peril. The six banded barb, Desmopuntius hexazonamay very well be a little bit boisterous, nonetheless as long as the halfbeaks have had ample to time to settle sooner than the barbs are added, they must be succesful to compete for enough meals to thrive collectively. A extra good selection nonetheless—calmer, although not found on the similar island—is the lambchop rasbora, Trigonostigma espei.
Eggs, not infants
The courtship of H. middle is correctly detailed by Dorn and Greven (chances are you’ll be taught the paper, along with see the fantastic courtship diagrams at tinyurl.com/47j793z8), nonetheless as I’ve not witnessed the full course of however I can’t go into any further non-public particulars. That acknowledged, my observations of the strategy up to now match up with the tales on this analysis.
Initially, a male defends a territory on the ground and when a female is attracted, he’ll perform a courtship dance transferring from the left of the female to the exact and once more as soon as extra, always staying behind or subsequent to her. With some beating of the male’s anal fin in opposition to the female, sperm is transferred to the genital pore which shall be saved for an unspecified time earlier to fertilisation. The female will deposit the eggs in a safe area, often in dense plant growths near the ground.
Research from totally different hobbyists current that they prefer to put eggs in tightly wound sections of woollen mops throughout the mop’s floatation machine, fairly than contained in the longer strands. The one eggs I’ve found have been located in floating stems of Limnophila sessilflora.
The one egg that effectively hatched occurred on the 18th day, nonetheless I do not know how prolonged it was laid sooner than I found it, or what stage it was at. I sadly did not deal with to get the individual to start out out feeding and misplaced it shortly after, no matter offering a mixed weight-reduction plan along with reside freshwater copepods, little one brine shrimp and rotifers along with some floating prepared fry diets (which have been supplied as a ultimate resort). I now have a convention of vinegar eels which I hope the movement and affinity to the meniscus might help the youthful halfbeaks to feed, I now merely have to hunt out the impossibly powerful to see eggs as soon as extra.
Borneo Redline Halfbeak Fact File
Scientific title: Hemirhamphodon tengah
Pronunciation: Hem-ee-ram-fo-don-ten-gah
Dimension: To 5cm
Origin: Southern Borneo
Habitat: Densely vegetated blackwater peat swamps
Tank dimension: 90x30x30cm
Water requirements: Mushy and acidic water; function for 5.5-6.5pH, 0-8°H,
Temperature: 25-28°C
Temperament: Peaceful nonetheless nervous species, not for a primary neighborhood
Feeding: Strictly takes floating meals, bear in mind frozen white mosquito larvae and small bugs along with flakes and floating pellets
Availability and value: Unusual to hunt out in retailers nonetheless accessible from specialist retailers, starting from spherical £7 each
