We have a 90x45x45cm tank with Corydoras catfish, cardinal tetras and rummynoses. We’d like to add some halfbeaks for the top of the tank. Will they work and what would be the best species to choose please?
JOHN & LINDA ROSE
NEALE SAYS: Halfbeaks are fascinating fish, and can make excellent additions to community tanks, provided their tankmates leave them alone. The species you have sound ideal, as they feed mostly from the middle and bottom levels of the tank. Corydoras and other small, inoffensive catfish are probably the ideal tankmates for halfbeaks. Tetras vary a bit, with the more surface-oriented ones, like splash tetras, likely to compete to some extent, but the bottom-dwelling species, such as cardinals, are much better.
In any case, when it comes to choosing halfbeaks for a mixed species tank, you’re basically limited to two options: Nomorhamphus and Dermogenys species.
Nomorhamphus species are often collectively sold as Celebes halfbeaks in the trade, though strictly speaking this name only refers to Nomorhamphus liemi. They tend to be relatively robust fish of 5-10cm long depending on the species, though invariably the males are smaller than the females. Their beaks are short, and often colourful, as in N. liemi, which sports patches of red, black, and blue on its beak and fins.
One problem with Nomorhamphus is that the various species all look rather similar at first glance, and it’s entirely possible that fish sold in one shop are a completely different species to those sold in another shop that uses a different supplier. For that reason, I’d recommend getting a decent batch of specimens when you see them, at least if you plan on breeding them. With all that said, N. liemi does seem to be by far the most common species in the trade thanks to its bright colours.
Once settled in, it’s quite hardy, but like all halfbeaks can be a bit delicate immediately after import. Nomorhamphus seem to do best in medium hardness water with a neutral pH, but what really matters is that water chemistry is stable. I kept and bred mine in a 50:50 mix of hard tapwater and rainwater with a pH of about 7.5 and around 10°GH hardness.
Dermogenys species are often sold as wrestling halfbeaks. Again, we have the problem here of multiple species being sold as Dermogenys pusilla, and to what extent this name defines a single species or encompasses a whole flock of species is a matter of scientific debate. Suffice it to say that telling apart such species as D. siamensis or D. sumatrana from ’true’ D. pusilla is easier said than done. So again, if you’re plann
