Banded Livebearer

Dermogenys pusilla, the Wrestling Halfbeak, is a distinctive surface-dwelling livebearer from South and Southeast Asia. Its strongly elongated lower jaw — the 'beak' — is immediately recognisable, and males engage in face-to-face beak-wrestling matches that are vigorous but rarely injurious, and are one of the hobby's more fascinating behavioural spectacles. The slender, silver-green body is beautifully streamlined for the surface film where the species spends its entire life.

In the aquarium it is best kept with abundant surface coverage from floating plants, which reduce stress and mimic the natural habitat of vegetated margins and rice paddies. Males can be kept together in groups if sufficient space is provided, though an excess of males relative to females will increase wrestling frequency. It is a livebearer producing relatively small broods of fully developed fry.

Fry are born large enough to accept micro live foods and small flake immediately, making this one of the easier livebearers to raise. The species is suitable for hard, slightly brackish water as well as fresh, reflecting its coastal and estuarine range.

Water: 22–28 °C, pH 7.0–8.0, moderately hard; tolerates low-level brackish conditions. Tank: 60 L minimum; floating plants for surface cover; open surface swimming areas. Feeding: Omnivore; surface micro-pellets, fruit flies, small insects, brine shrimp nauplii. Breeding: Livebearer; broods every 4–6 weeks; fry accept micro-foods immediately. Compatibility: Surface fish; peaceful with mid-water and bottom species.