Green Neon Tetra Breeding Guide

Breeding Paracheirodon simulans: sexing, the very soft tannin-stained blackwater required, light-sensitive eggs, and rearing fry.

Overview

Paracheirodon simulans is a small tetra of the upper Orinoco and Negro Rivers, growing to roughly 1-2 cm in standard length. Its native blackwater habitat is extremely soft and acidic, occupying the uppermost portions of tributaries, with recorded pH between 4.3 and 4.7 and dissolved oxygen as low as 0.7-4.4 mg/L. It is listed as Least Concern on the IUCN Red List, with the aquarium trade being its only known threat. The species is not bred on a commercial basis, which makes it harder to find and reflects the demanding conditions needed to spawn it.

Sexing

Sexually mature females are normally noticeably rounder-bodied and a little larger than males.

Breeding Setup

Successful breeding demands very specific water: extremely soft, with a pH of about 6 and a temperature around 25 C, heavily stained by tannins from peat, in subdued light. These conditions recreate the soft, dark waters of the natural range.

Spawning Behavior & Trigger

Females can produce about 130 eggs per batch. As an egg-scattering characin, the fish should be conditioned and spawned over a fine-leaved medium in the dimly lit, soft, peat-stained tank. Adults can breed again after a few weeks.

Egg & Fry Care

Eggs hatch in about 24 hours but are light sensitive, so the tank must be kept dark in the early stages. Newly hatched fry require infusoria initially, later transitioning to commercial fry foods as they grow.

Common Challenges

The need for very soft, acidic, tannin-rich water and the light sensitivity of the eggs make this an advanced project; most aquarium stock is wild-caught because the species is not bred commercially, with roughly 17,000 individuals recorded as exported in 2002. Matching the soft, dark, low-oxygen character of the natural range as closely as possible is the key to coaxing the fish into spawning.