Rainbow Emperor Tetra

Nematobrycon lacortei

Animalia›Chordata›Actinopterygii›Characiformes›Characidae

📍 Río San Juan, Colombia

Close relative of the Emperor Tetra with vivid red eyes and a blue-green iridescent body. Males develop stunning red-orange caudal fins.

Size2"

Min Tank15g

School6+

peaceful

Zonemid

Care Guide

Diet

Rainbow Emperor Tetras are omnivores that thrive on a varied diet of high-quality flake foods, micro pellets, and small frozen foods like brine shrimp, daphnia, and bloodworms. Feed small portions once daily, offering only what they can consume in 2-3 minutes. Occasional vegetable matter such as blanched spinach or algae-based supplements supports digestive health.

Behavior

These peaceful, schooling fish are most active during midday hours and display their best coloration when kept in groups of at least 6 individuals. Males exhibit territorial displays with fin flaring and color intensification, particularly the striking red-orange caudal fins, but rarely cause serious harm to tank mates. They prefer moderate water flow and appreciate dimly lit areas with vegetation for security.

Breeding

Breeding Rainbow Emperor Tetras in captivity is difficult and rarely achieved by hobbyists. They require soft, acidic water (pH 5.0-6.0), dense vegetation or spawning mops, and careful conditioning of breeding pairs with live foods. Fry are extremely small and require infusoria or liquid fry food for the first week before accepting micro foods.

Tank Mates

Neon Tetra

Similar size, water parameters, and peaceful temperament; excellent community fish

excellent

Cardinal Tetra

Comparable size and requirements; both prefer soft, acidic water and mid-water swimming zones

excellent

Otocinclus

Peaceful bottom-dweller that won't compete for food or space; helps maintain tank cleanliness

good

Red Cherry Shrimp

Small shrimp are generally safe with tetras; provide algae control and occupy different water zones

good

Dwarf Gourami

Generally peaceful but can be territorial; monitor for aggression, especially during breeding

caution

Common Diseases

Ich (Ichthyophthirius multifiliis)

Symptoms

White spots on body and fins, rapid breathing, lethargy, rubbing against objects

Treatment

Raise temperature gradually to 28-29°C, perform daily 25% water changes, use aquarium salt (1 teaspoon per 5 gallons) or commercial ich treatment for 7-10 days

Fin Rot

Symptoms

Frayed or deteriorating fin edges, discoloration at fin bases, lethargy

Treatment

Improve water quality with frequent partial water changes, reduce stocking density, use antibacterial medication if severe; ensure pH and temperature stability

Neon Tetra Disease

Symptoms

Loss of coloration, spinal curvature, erratic swimming, white stripe along lateral line

Treatment

No cure exists; isolate affected fish to prevent spread, maintain pristine water conditions, consider euthanasia if severely affected

Bacterial Infection

Symptoms

Cloudy eyes, open sores, torn fins, loss of appetite, color fading

Treatment

Perform 50% water change immediately, treat with broad-spectrum antibiotic medication, maintain temperature at 25-26°C, improve filtration and water quality