Wrestling Halfbeak

Dermogenys pusilla

Livebearers

A unique, surface-dwelling livebearer known for its elongated, pike-like lower jaw. Males are famous for 'wrestling' by locking jaws to establish dominance. They are strictly top-dwellers and excellent jumpers, requiring a tight-fitting lid to prevent escapes and snout injuries. They prefer hard, alkaline water and thrive in both freshwater and slightly brackish conditions.

At a Glance

Adult Size7 cm
Body ShapeFusiform
Growth RateModerate
TemperamentMostly Peaceful
Water TypeBrackish Tolerant
Flow PreferenceModerate
Waste OutputLow
StockingGroup of 4+

Tank Requirements

Minimum Volume55 L
Minimum Length60 cm
FlowModerate
Water TypeBrackish Tolerant
Must-Haves in the Tank
Plants - Floating

Water Parameters

Temperature2428°C
pH78.5
Hardness1020 dGH

Temperament & Compatibility

Aggression LevelMostly Peaceful
4/10
Where They Swim
Surface
Mid-level
Bottom
Stocking Guidelines
Keep at Least4 fish
Max per TankNo limit
Can Live Alone?No — needs a group
Behavior Traits
Jumper (Lid Required)Hyperactive / Fast SwimmerFry PredatorAggressive to same species/look-alikes

Available Varieties

Each variety inherits the species defaults above. Only differences are highlighted.

Female

Females are significantly larger than males (up to 7cm) and lack red/yellow coloration on their fins. They are generally peaceful and should outnumber males (e.g., a 2:1 or 3:1 ratio) to minimize harassment from constant breeding attempts.

Differs in 2 traits from base species

Also known as: Standard, Female Halfbeak

TemperamentPeaceful
Behavior Traits
Jumper (Lid Required)Hyperactive / Fast SwimmerFry Predator

Male

Males are much smaller (around 4cm), more colorful, and highly territorial. They frequently lock their delicate jaws to 'wrestle' for dominance. It is best to keep only one male per tank unless the tank is large enough (90cm+) to disperse aggression and establish distinct territories.

Differs in 3 traits from base species

Also known as: Wrestling Male, Silver

Adult Size4 cm
TemperamentSemi-Aggressive
Behavior Traits
Jumper (Lid Required)Hyperactive / Fast SwimmerFry PredatorAggressive to same species/look-alikes

Wrestling Halfbeak Care Guide Summary

The Wrestling Halfbeak, scientifically known as Dermogenys pusilla, belongs to the Livebearers family group. Adults reach a maximum size of approximately 7 cm and have a fusiform body shape with a moderate growth rate. Classified as mostly peaceful, this species primarily occupies the surface zone of the aquarium and produces a low level of biological waste.

To thrive, the Wrestling Halfbeak requires a brackish tolerant aquarium with a minimum volume of 55 litres and a tank length of at least 60 cm. Water temperature should be maintained between 24°C and 28°C, with a pH range of 78.5 and a general hardness of 1020 dGH. A moderate water flow is preferred.

The Wrestling Halfbeak is a rewarding species to keep, provided its core environmental needs are met. This species is available in 2 varieties: Female and Male. Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.

Wrestling Halfbeak Habitat Setup

When setting up an aquarium for the Wrestling Halfbeak, a moderate water flow best suits their natural preferences. Because this species occupies the surface zone, the aquarium layout should prioritise adequate surface area with floating cover to make them feel secure near the waterline. Useful additions include floating plants to diffuse overhead light and create shaded areas. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.

Wrestling Halfbeak Compatibility Notes

Classified as mostly peaceful, the Wrestling Halfbeak is a social species that requires the company of its own kind to thrive. When choosing tankmates, conspecific aggression can be intense, especially in smaller tanks and their energetic swimming style may stress more sedentary or timid species. Selecting tankmates that favour different water layers from the surface zone can help reduce competition and territorial overlap.

Frequently Asked Questions About Wrestling Halfbeak

How big does Wrestling Halfbeak get?+
Wrestling Halfbeak (Dermogenys pusilla) typically reaches a maximum adult size of approximately 7 cm. They have a fusiform body shape and a moderate growth rate.
What tank size does Wrestling Halfbeak need?+
A minimum aquarium volume of 55 litres and a tank length of at least 60 cm are recommended for Wrestling Halfbeak. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Wrestling Halfbeak need?+
Wrestling Halfbeak thrives in brackish tolerant conditions with a temperature range of 24–28°C, a pH between 7 and 8.5, and a general hardness of 10–20 dGH. A moderate water flow is preferred.
Is Wrestling Halfbeak peaceful or aggressive?+
Wrestling Halfbeak is classified as mostly peaceful with an aggression score of 4 out of 10. They are generally well-suited to peaceful community tanks.
Can Wrestling Halfbeak live alone?+
No, Wrestling Halfbeak should be kept in groups of at least 4 to reduce stress and encourage natural behaviour.
Does Wrestling Halfbeak have any special tank requirements?+
Yes. Wrestling Halfbeak benefits from plants - floating in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Wrestling Halfbeak need a lid on the tank?+
Yes. Wrestling Halfbeak is a known jumper, and a tight-fitting lid or cover is essential to prevent escape. Even a small gap can be enough for a determined fish to leap out.

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