Tank Setup
- Tank size: 30 gallons minimum for a school of 6. 55 gallons for 10–12 is ideal to see their full behavior.
- Lighting: Moderate — their iridescent scales produce the best shimmer under indirect or diffused light
- Plants: Heavily planted perimeter with open center for schooling. Use plants they can't easily eat — java fern and anubias are good choices. Congo tetras may nibble on tender plants.
- Substrate: Dark sand dramatically enhances their rainbow iridescence
- Flow: Gentle — strong current damages their flowing fins
Water Parameters
- Temperature: 73–82°F (23–28°C)
- pH: 6.0–7.5 (slightly acidic preferred)
- GH: 3–12 dGH
- Ammonia/Nitrite: 0 ppm
- Nitrate: below 20 ppm
Appearance & Sexual Dimorphism
Males are significantly more colorful than females, with elongated, flowing dorsal and caudal fins that develop as they mature (6–8 months). The iridescent body shimmers through blue, green, gold, and violet depending on the angle and lighting. Females are smaller, less colorful, and have shorter fins.
Diet & Feeding
- Staple: High-quality flakes or medium-sized pellets
- Supplements: Frozen bloodworms, brine shrimp, daphnia — these enhance coloration
- Note: Congo tetras may nibble on soft-leaved plants when underfed. Ensure they get enough food to prevent plant damage.
Tank Mates
Congo tetras are timid despite their size. Pair with calm, peaceful species:
- Other peaceful tetras (rummy nose, ember)
- Corydoras, kuhli loaches, bristlenose plecos
- Dwarf gouramis, angelfish (in 55+ gallon tanks)
Avoid nippy species like serpae tetras and tiger barbs — they will shred the Congo's flowing fins, causing permanent damage and stress.
Frequently Asked Questions
Why are my Congo tetras not colorful?
Males take 6–8 months to develop full coloration and fin length. Stress, poor water quality, inadequate diet, and bright lighting can all suppress color. Dark substrate, soft water, and a varied diet with frozen foods will bring out the best colors.
Do Congo tetras eat plants?
They can nibble on tender plants, especially when underfed. Stick to tough plants like java fern, anubias, and vallisneria. Provide enough food and they'll leave plants alone.