Pristella Tetra Breeding Guide

Breeding Pristella maxillaris: sexing, group or pair egg-scattering in soft acidic water, light-sensitive eggs, and rearing fry.

Overview

Pristella maxillaris is a hardy, semi-transparent tetra of about 3-5 cm from northern South America (Venezuela and Guyana), commonly called the X-ray tetra for its translucent body. Although it is adaptable in general care across a wide pH range, it is an egg-scattering free spawner that requires soft, acidic conditions to breed reliably. Both eggs and fry are light sensitive in the early stages.

Sexing

Mature females are usually bigger and noticeably stockier than males, while males display more vibrant colouration.

Breeding Setup

Use a dedicated tank of roughly 18 by 10 by 10 inches, kept very dimly lit, with fine-leaved plants such as java moss or spawning mops, or a mesh base that lets eggs fall through while keeping adults away. Soft, acidic water of pH 5.5-6.5, hardness 1-5, and a temperature of around 27-29 C suits spawning; filtering through peat or using RO water is beneficial.

Spawning Behavior & Trigger

Two methods work. For group spawning, condition about half a dozen of each sex on live foods and remove the adults once eggs are visible. For pair spawning, condition the sexes separately, then transfer the fattest female and best-coloured male to the spawning tank in the evening for a morning spawn.

Egg & Fry Care

Eggs hatch in 24-36 hours, and the fry become free-swimming three to four days later. Keep the tank dark in these early light-sensitive stages. Start the fry on an infusoria-type food, progressing to microworm or brine shrimp nauplii once they are large enough.

Common Challenges

Although the adults are hardy, getting eggs to develop requires the soft, acidic, dim conditions described, and the light sensitivity of the early stages means the tank must be shaded. Filtering the breeding water through peat or using reverse-osmosis water helps reach the required softness and acidity, and the choice between group and pair spawning lets the breeder work either with a conditioned shoal or with a single selected pair.