Dwarf Neon Rainbowfish

Dwarf Neon Rainbowfish (Melanotaenia praecox) Also known as the Praecox Rainbowfish or Dwarf Rainbowfish

A small and brilliantly colored freshwater rainbowfish endemic to the Mamberamo River system in northern Irian Jaya (West Papua), Indonesia. One of the smallest members of the Melanotaenia genus, this compact species is highly prized in the aquarium hobby for its stunning iridescent colors that develop even at a young age and its unique deep-bodied shape in males.

Key Features

• Maximum Size: 5.0 cm / ~2 inches SL (commonly around 4 cm; one of the smallest rainbowfishes).
• Appearance: Sleek, fusiform body that becomes noticeably deep-bodied, especially in males, at a remarkably small size (3.0–3.5 cm SL). Males display vibrant metallic neon blue to silvery-blue coloration with intense iridescence and bright blood-red accents in the fins. Females are slimmer with softer silvery to pale golden tones.
• Fin Details: Dorsal spines 5–7, dorsal soft rays 10–14; anal spines 1, anal soft rays 16–21.

Aquarium Care

• Tank Size: Minimum 30–40 gallons (80 cm length) for a small school (6 or more recommended for best coloration and natural behavior).
• Water Parameters: Tropical freshwater; 72–82°F (22–28°C), pH 6.5–8.0, moderate hardness.
• Diet: Omnivorous — readily accepts high-quality flakes, pellets, frozen, and live foods. A varied diet enhances coloration.
• Behavior: Peaceful, active mid-to-upper water column schooling fish. Excellent for planted nano to medium community aquariums with similarly sized, non-aggressive companions. Provide open swimming space and a tight-fitting lid as they are strong jumpers.

IUCN Status Least Concern (LC)

Add shimmering neon blue brilliance and fiery red accents in a compact, lively package with the beautiful Dwarf Neon Rainbowfish!