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Silver Half Beak (Dermogenys pusilla)
Silver Half Beak (Dermogenys pusilla)
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$22.00 NZD
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The silver half beak (Dermogenys pusilla), more commonly known as the wrestling halfbeak or Malayan halfbeak, is a slender, surface-dwelling livebearing fish native to Southeast Asia. It is best known for its asymmetrical jaws, where the lower jaw extends far beyond the shorter upper jaw to form a needle-like "half beak".
Physical Characteristics
- Body shape. They have a streamlined, torpedo-like body designed for darting along the water's surface. Most of their fins, including the dorsal and anal fins, are positioned far back near the tail.
- Unique mouth structure. The lower jaw is elongated and rigid, while the much shorter upper jaw hinges upward to open the mouth and snatch prey from the surface.
- Coloration. Wild specimens typically have a shimmering silvery-white to olive-grey body that acts as camouflage from predators. Aquarium strains bred for bright metallic sheen are commonly sold as "silver" or "platinum" halfbeaks.
- Size and sexual dimorphism. Females are noticeably larger and fuller-bodied, reaching up to 7 cm (2.8–3 inches). Males stay smaller at around 5.5 cm (2.2 inches), possess a modified anal fin (andropodium) for internal fertilization, and often display red, yellow, or black markings on their fins and beak.
Habitat and Behaviour
- Surface lifestyle. They spend almost all their time just beneath the water's surface, feeding on small insects, mosquito larvae, and crustaceans that fall onto the water.
- Male sparring. The nickname "wrestling halfbeak" comes from the territorial behavior of males, which lock their elongated jaws together and wrestle for dominance.
- Reproduction. Unlike most egg-laying fish, silver halfbeaks are livebearers. After a gestation period of roughly 3 to 8 weeks, females give birth to 10 to 30 free-swimming fry.
- Tank setup. A minimum of 60 to 75 litres with a large surface footprint, gentle filtration, floating plants for cover, and a tight-fitting lid because they are strong jumpers.
- Water parameters. Temperature between 24–28°C (75–82°F), pH of 6.5–8.0, and moderate to hard water (10–20 dGH).
- Social grouping. Peaceful toward other small, calm tankmates, though they should be kept either as a single male with multiple females or in larger groups of six or more to disperse male rivalry.
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