Forktail Blue-eye

Geographic Origin and Biotope: Papua New Guinea. Populates shaded forest rivers and streams with dense aquatic vegetation, clear water and moderate flow, often in limestone areas.

Taxonomy and Morphology: Forktail Blue-eye (Pseudomugil furcatus). Melanotaeniid. Characterized by two close dorsal fins (typical of blue-eyes). Penetrating iridescent blue eyes and forked tail (furcatus).

Social Behavior: Extremely gregarious and choreographic. Males swim shoulder to shoulder performing elaborate "Sparring dances", snapping their yellow fins up and down to intimidate each other and attract females, without ever getting hurt.

Coloration and Sexual Dimorphism: Spectacle in yellow. The body is semi-transparent golden. Males exhibit wide bright sunshine yellow margins on all fins and black stripes on the margins of the tail. Females are paler, with short, transparent fins.

Aquarium Setup: 80 cm (32 inches) tank. It is essential to provide ample space for open swimming and thick bushes of stem plants (Myriophyllum, Rotala) where males can establish temporary mini-territories and females can hide.

Diet and Feeding: Micro-insectivore. They have very small mouths and narrow throats. They only eat food floating in mid-water or on the surface. Live brine shrimp nauplii are the ideal food to trigger golden reflections.

Water Quality: Hard water lovers. Unlike Amazonian fish, they tolerate soft and acidic waters poorly. They require a pH between 7.0 and 8.0 and a medium-high GH to maintain perfect osmoregulation and avoid bacterial collapse.

Compatibility and Tankmates: Peaceful community fish, perfect with other Rainbowfish, Corydoras and Loricariids. Not recommended to pair with aggressive fish, slow eaters (they would be outcompeted) or male Bettas (who would mistake their yellow fins for a threat).

Aquarium Reproduction: Continuous scatterers. Females release a few adhesive eggs among the mosses every morning. Parents will eat their own eggs and larvae; to save the fry (which hatch in 15 days), use wool Mops and transfer them.

Risks and Diseases: Competition Exhaustion. Males in a group with few females will engage in challenges so grueling that they will end up losing weight, wearing out their fins and dying prematurely. Always maintain a ratio of 1 male to 2-3 females.