Green Neon Tetra

The Green Neon Tetra (Paracheirodon simulans) is the "connoisseur's" tetra. While it shares the name with its more famous cousins, the Neon and Cardinal Tetras, it is a distinct species with a very different aesthetic. Instead of the half-body red stripe of a Neon, or the full-body red of a Cardinal, the Green Neon has only a very faint, washed-out red patch near the tail, or lacks it entirely.

Its primary feature is a magnificent, glowing lateral line that appears electric blue or emerald green depending on the light and the dark water conditions it prefers. It is also the smallest of the three, rarely exceeding 1 inch (2.5 cm) in length.

Natural Habitat & Origin

This species is native to the upper Rio Negro basin in Brazil and the Rio Orinoco in Venezuela. It is a true blackwater specialist, inhabiting the "igapó" (flooded forests) and shallow, tea-colored streams. The water in these habitats is extremely soft, virtually mineral-free, and highly acidic due to the massive concentrations of dissolved tannins and humic acids from decaying leaf litter.

Care Requirements

The Green Neon Tetra is more sensitive than the standard Neon and is best suited for established, stable aquariums. They require very soft water (GH 1-5) and acidic conditions, ideally with a pH between 4.5 and 6.0. They also prefer slightly warmer water than standard Neons, ranging from 75°F to 86°F (24°C to 30°C).

A minimum tank size of 10 gallons (40L) is sufficient for a school. The setup should feature a dark substrate and plenty of driftwood or leaf litter (like Catappa or Guava leaves) to provide the tannins they need to feel secure and display their best colors. Floating plants are highly recommended to provide the subdued lighting they prefer.

Diet & Feeding

They are social omnivores that feed on tiny invertebrates, zooplankton, and organic detritus in the wild. In the aquarium, they are not picky but require small, high-quality foods. Crushed flakes, microperls, and frozen baby brine shrimp or daphnia are excellent choices. Frequent, small feedings are better than one large one, as they have high metabolisms and small stomachs.

Behavior & Temperament

Green Neon Tetras are exceptionally peaceful and should always be kept in schools of at least 8-10 individuals. Because they are so small and docile, they can be easily intimidated by larger or more boisterous fish. When kept in a proper school in a blackwater setup, they are relatively active and will spend most of their time shoaling through the mid-levels of the tank.

Tank Mates

Suitable tank mates are other small, peaceful species from similar blackwater environments:

Other small Tetras (Tucano Tetra, Ember Tetra)
Pencilfish
Pygmy Corydoras
Dwarf Cichlids (Apistogramma, Dicrossus)
Otocinclus

Avoid housing them with any fish large enough to see them as food, including many "medium" community fish, as their small size makes them very vulnerable.

Breeding

Breeding Paracheirodon simulans is a significant challenge in captivity. Like many blackwater species, their eggs and fry are extremely sensitive to light and water hardness. Spawning requires extremely soft (0-1 dGH) and acidic (pH 4.0-5.0) water. They are egg-scatterers, and the parents must be removed immediately after spawning. The fry are microscopic and require infusoria or paramecium as their first food. Success stories are rare in the home hobby.

Common Health Issues

They are particularly sensitive to "Neon Tetra Disease" (Pleistophora hyphessobryconis) and sudden shifts in water chemistry. They can also be prone to fungal infections if the water quality is poor or if the pH is too high. Maintaining stable, acidic, and tannin-rich water is the best way to prevent stress and disease in this delicate species.