Kali Datu Rainbowfish

Kali Datu Rainbowfish ( Melanotaenia sp. "Kali Datu" )

A highly sought-after undescribed species originating from the Bird's Head Peninsula of West Papua, Indonesia. This small, locality-specific rainbowfish is prized in the aquarium hobby for its vivid metallic body and striking red-and-blue coloration that becomes significantly more intense as the fish matures. It is closely related to the Kali Tawa Rainbowfish and belongs to a group of attractive dwarf Melanotaenia forms.

• Maximum Size: Small-to-dwarf growing; typically reaches 8–10 cm (approx. 3–4 inches) TL. Males are generally more robust and intensely colored than females.
• Appearance: Sleek body with a bright metallic sheen. Mature specimens, especially males, display vivid red and blue coloration that intensifies dramatically with age and optimal conditions. The overall effect is a striking metallic red-and-blue fish that stands out in well-lit aquariums.
• Fin Details: Dorsal spines 6–7, dorsal soft rays 10–12; anal spine 1, anal soft rays 17–20.

Aquarium Care

• Tank Size: Minimum 30 gallons to properly house a school.
• Water Parameters: Tropical freshwater; 75–78°F (24–26°C), slightly basic pH (approximately 7.0–8.0).
• Diet: Omnivorous. Readily accepts high-quality flakes, micro-pellets, and a variety of live or frozen foods such as brine shrimp and daphnia.
• Behavior: Highly peaceful and active schooling fish. They make excellent additions to community tanks, where they occupy the mid-to-upper water column. They display their best color and natural behavior when kept in groups of 6 or more. A secure lid is recommended as they can be jumpers.

IUCN Status: As an undescribed species, this population has not been formally assessed by the IUCN. Like many localized West Papuan rainbowfish, habitat protection is important for its long-term survival in the wild.