GloFish Blue Tetra (Cosmic Blue Skirt Tetra) – ~2.5–3 inches

The GloFish Blue Tetra is a genetically enhanced version of the Black Skirt Tetra (Gymnocorymbus ternetzi), designed to display a dazzling cosmic-blue fluorescence. This neon glow is permanent and especially vivid under actinic or blue-spectrum lighting.

Size

Reaches about 2–2.5 inches (5–6 cm) in adulthood.

Behavior & Social Needs

Peaceful schooling fish, happiest when kept in groups of 6 or more. Keeping them in larger groups encourages schooling behavior and prevents nipping or chasing.

💡 Hobbyist insight: “My smaller group had chasing, but when I upped to 6+, they schooled beautifully.”
 

Tank Conditions

• Tank Size: At least 15–20 gallons for a healthy school.

• Temperature: 72–80 °F (22–27 °C).

• pH: 6.0–7.5; water: soft to moderately hard.

• Lighting: Blue/actinic LED light maximizes the fluorescent glow, though normal daylight lighting is fine.

• Decor Tips: Dark gravel, driftwood, and lush plants (including floating cover) enhance their glowing blue color.

Diet

Omnivorous: Provide tropical flakes or micro-pellets as a staple diet. Supplement with frozen/live foods like brine shrimp, daphnia, or bloodworms to maintain strong colors and health.

Lifespan & Hardiness

Beginner-friendly and hardy, averaging 3–5 years in lifespan, with some living up to 7 years under optimal care.