The Emperor Tetra (Nematobrycon palmeri) is a regal, peaceful freshwater fish native to the Atrato and San Juan River basins in western Colombia. Known for its iridescent blue-purple sheen, striking yellow fins, and unique trident-shaped tail, it is a highly popular, hardy choice for community aquariums.
Quick Care OverviewCare Level: EasyLifespan: 3 to 6 yearsAdult Size: 4 to 5 cm (up to 7.5 cm for mature males)Minimum Tank Size: 60 Litres (approx. 15–20 gallons)Diet: Omnivorous micropredator
Tank Setup & Water ParametersEmperor Tetras thrive in setups that mimic their slow-moving, forested natural river habitats.
Environment: Use a dark substrate and include heavy live vegetation (like Java Moss) alongside driftwood roots to create secure hiding places. Subdued, lower lighting will make them comfortable and cause their colors to pop beautifully.Temperature: Keep the water stable between 23°C and 27°C.pH Range: They prefer slightly acidic to neutral water between 6.0 and 7.5.Water Flow: Maintain a slow to moderate flow, avoiding powerful or boisterous powerheads.
Diet & FeedingIn captivity, they are undemanding, highly active eaters. Feed them a varied core diet using high-quality flakes or micro pellets. Periodically supplement their meals with frozen or live foods like baby brine shrimp, daphnia, or bloodworms to keep them healthy and vibrant.
Behaviour & Ideal TankmatesThese are peaceful schooling fish that should be kept in groups of 6 or more. Keeping them in a school spreads out minor territorial squabbles among males and encourages natural displaying.
Good Tankmates: Pair them with other calm species such as small Corydoras catfish, danios, rasboras, pencil fish, or dwarf cichlids.Avoid: Very large, aggressive, or fast, boisterous swimmers that might intimidate them or nip at their long fins.
Gender IdentificationTelling males and females apart is relatively easy once they mature:
Males: Larger, boasting a prominent trident-shaped extension in the center of their tail fin and an unmistakable, luminescent bright blue eye.
Females: Plumper, slightly smaller, lacking the elongated tail extension, and exhibiting a distinct greenish-yellow eye
