Red Rainbowfish

The Red Rainbowfish (Glossolepis incisa), often sold as the Red Irian Rainbowfish or Salmon Red Rainbowfish, is a striking freshwater fish famous for its deep, vibrant crimson color. Native exclusively to Lake Sentani in West Papua, Indonesia, these active, schooling fish are a highly prized centerpiece species for medium to large community aquariums.

Species Overview & Care Guide

Attribute	Specification
Scientific Name	Glossolepis incisa (often misspelled as incisus)
Adult Size	Up to 6 inches (15 cm)
Minimum Tank Size	50–55 gallons (at least 4 feet long)
Temperature Range	72°F to 82°F (22°C to 28°C)
Water Chemistry	pH: 7.0–8.0
Diet	Omnivorous (Requires high-protein foods to maintain red color)
Temperament	Peaceful, but very fast and energetic

Tank Setup & Behavior

Schooling Dynamics: They must be kept in groups of 5 or more (ideally balanced with one male to every two females). Keeping them in groups reduces aggression and stimulates the males to flash their brightest colors while competing for female attention.
Aquarium Decor: These fish look best against a dark substrate in a well-planted aquarium. Ensure you leave plenty of open swimming space in the center, as they are constant, rapid swimmers.
Juvenile Drabness: Do not be discouraged if they look olive-brown or silver at the pet store. Rainbowfish juveniles are naturally plain and will only develop their signature blinding red coloration once they mature and settle into a stable environment.

Gender Differences (Sexual Dimorphism)

Males: Bright, cherry-red bodies that grow a distinctively high, arched back as they age.
Females: Much more understated, featuring an olive-brown or brassy-silver body with smaller fins. [1, 2]