绿莲灯 · Green Neon Tetra

Overview

Paracheirodon simulans, the green neon tetra, has a blue-green stripe extending to the tail base and a relatively small, subdued red area on the flanks. Its tiny size and need for stable blackwater conditions make careful planning more useful than simply adding it to a general community.

Distribution & habitat

It occurs in the middle and upper Negro drainage in Brazil and in the Orinoco system along the Colombian–Venezuelan border. It occupies blackwater in the upper, terra firme portions of tributaries rather than the regularly flooded lowlands.

Typical sites have slow to moderate flow, dense bankside vegetation, and sand strewn with branches, roots, and leaves. Decomposing organic material stains the acidic water brown; carbonate hardness and conductivity are extremely low. Although the broad range overlaps that of Paracheirodon axelrodi, the two are not found together, and green neon tetras tend to occupy warmer sites.

Aquarium setup

Allow a footprint of at least about 45 × 30 cm. Dense planting or a sand-and-wood layout with branches and leaf litter supplies cover. Keep lighting subdued and use shade-tolerant or floating plants. Microorganisms developing on decomposing leaves can supplement fry nutrition.

Trade specimens are wild-caught and may be particularly sensitive soon after import. Use a biologically mature aquarium and prevent deteriorating or abruptly changing water conditions. High temperatures recorded in natural habitats describe environmental exposure and tolerance; the upper limit is not an everyday heating target.

Diet & feeding

Wild fish probably consume a mixture of small invertebrates, crustaceans, filamentous algae, and fallen fruit. Provide more than dry food in captivity: appropriately sized live or frozen Daphnia, Moina, mosquito larvae, and bloodworms can add variety.

Behaviour & compatibility

This peaceful fish is best kept as a single-species group, or with very small, non-aggressive characids and suitable small catfishes. Its size and particular water requirements narrow the choice of companions. Keep at least 8–10 individuals to reduce shyness and encourage more varied social behavior.

Sexual dimorphism

Mature females are usually slightly larger and noticeably rounder than males.

Notes

Useful identification features are the greener reflective stripe reaching the caudal-fin base and the reduced, duller red flank pigmentation. Colors become subdued at night, when the stripe can look violet, and intensity can also change with lighting and background.

Golden metallic scales occur in some wild specimens marketed as “gold” or “platinum.” A proposed explanation involves parasites stimulating guanine deposition, so the appearance should not automatically be treated as a separate strain. Predator confusion through reflected light from the bright stripe is likewise a research hypothesis.