Rainbow Tetra (Nematobrycon lacortei) — > 3cm

Overview

The Rainbow Tetra (Nematobrycon lacortei) is a small, peaceful Colombian tetra celebrated for its shimmering rainbow coloration and gentle demeanor. Endemic to the San Juan and Calima river basins in Colombia, this species thrives in planted community aquariums with soft to moderately hard water. Available for sale UK-wide, the Rainbow Tetra is an excellent choice for aquarists seeking a colorful, active schooling fish with moderate care requirements and a captivating, peaceful nature.

Appearance and Coloration

Nematobrycon lacortei displays a slender, elongated body with iridescent coloration that shifts between blue, green, gold, and violet depending on lighting and mood. Males are more colorful and may exhibit extended finnage and more pronounced iridescence during courtship. The species has a distinctive black lateral stripe that runs from the snout to the caudal fin, creating a striking contrast against the shimmering body. Large, expressive eyes and delicate, translucent fins complete the elegant profile.

Natural Habitat

The Rainbow Tetra is endemic to the San Juan and Calima river basins in Colombia, where it inhabits slow-moving streams and tributaries with dense vegetation, submerged wood, and leaf litter. These habitats feature soft to moderately hard water, moderate temperatures, and subdued lighting beneath forest canopy. The fish form small schools in the wild, sheltering among plants while foraging for small invertebrates and organic matter.

Aquarium Setup

A minimum 75-litre aquarium is recommended for a school of Rainbow Tetras. Provide dense planting using species like Amazon Sword, Cryptocoryne, Java Fern, or Vallisneria, combined with driftwood and smooth rocks to create hiding places and territorial markers. Subdued or dim lighting reduces stress and enhances the fish's iridescent coloration. Gentle filtration maintains water quality without creating excessive current, as this species prefers calm to moderate flow.

Water Parameters

Maintain soft to moderately hard water with pH 5.5-7.5 and temperatures between 23-28°C. General hardness (GH) of 5-10 dGH is ideal. The Rainbow Tetra is moderately adaptable but performs best in mature, well-established aquariums with stable parameters. Perform weekly water changes of 20-25% to control nitrate and maintain water quality. Avoid hard, alkaline water and strong current, which stress this gentle species.

Feeding and Diet

Nematobrycon lacortei is an omnivore that thrives on a varied diet. Offer high-quality micro-pellets or flakes as a staple, supplemented with small frozen and live foods such as daphnia, brine shrimp, bloodworms, and cyclops. Occasional plant-based matter or spirulina-based foods provide balanced nutrition and enhance coloration. Feed small portions 1-2 times daily, ensuring food is consumed within a few minutes to prevent water quality issues.

Behaviour and Personality

The Rainbow Tetra is a peaceful, schooling fish that thrives in groups. Shoaling behavior is most pronounced when kept in larger numbers, with fish moving together in coordinated, shimmering patterns. This species occupies the mid to upper water column and is most active during feeding times. Males may engage in mild sparring over territory or mates, but this is rarely aggressive and adds to the visual interest of the species.

Tank Mates

Ideal tank mates include small peaceful tetras, rasboras, Corydoras catfish, small peaceful dwarf cichlids, and Otocinclus. Avoid large predatory fish, fin-nipping species, aggressive cichlids, and very boisterous tankmates. The Rainbow Tetra coexists well with similarly sized, peaceful community fish in a well-planted, dimly lit aquarium.

Breeding

Nematobrycon lacortei spawns readily in soft, slightly acidic water with fine-leaved plants or spawning mops. Breeding is most successful in a separate spawning tank with pH 6.0-6.5, subdued lighting, and gentle filtration. Condition adults with live foods, then introduce a pair or small group. Adults may eat eggs, so remove them after spawning. Fry are tiny and hatch in 24-48 hours, requiring infusoria or liquid fry food initially before graduating to baby brine shrimp as they grow.

Why Buy from Tropical Fish Co

Tropical Fish Co specializes in healthy, vibrant South American tetras sourced from reputable suppliers and quarantined for your peace of mind. We provide expert guidance on planted tank setup, water chemistry, and compatible stocking to help you create a thriving community aquarium. With fast, reliable delivery across the UK and a commitment to sustainable fishkeeping, Tropical Fish Co is your trusted partner for quality freshwater fish.