Freshwater Halfbeak

About

The freshwater halfbeak (Dermogenys pusilla) takes its name from the dramatically elongated lower jaw that characterizes the entire halfbeak family, and the 'wrestling' nickname it sometimes carries is well earned. Males are known to lock jaws and spar with one another, a behavior historically exploited in parts of Southeast Asia where males were pitted against each other for sport. In the wild, this species occupies a wide range of slow-moving and still waters across Java and the broader Southeast Asian region, from canals and drainage ditches to flooded fields, almost always near floating or emergent surface vegetation. In the aquarium it stays close to the top of the water column, which makes it an interesting addition to a peaceful community as long as tankmates are similarly sized and not aggressive enough to push it off food. Males will spar regularly in captivity, but in a properly sized tank the subordinate fish can usually retreat before any real harm is done. Keeping several males together tends to spread out the aggression better than keeping just two. Breeding is achievable but has a catch. Females can deliver stillborn fry when their diet is inadequate, so feeding a varied and nutritious menu is important. Fry are reasonably straightforward to raise once healthy broods are produced.