Translucent Danionella (Danionella translucida) Breeding Guide

Breeding the tiny transparent Danionella translucida: sexing, small continuous spawns, fine substrate or moss, and rearing extremely small fry.

Overview

Danionella translucida is a tiny cyprinid endemic to Myanmar (Pegu Division), measuring about 1.1 cm and almost perfectly transparent except for its eyes (Wikipedia). It inhabits a slow-flowing, shallow stream up to about 1 m deep among floating plant roots. Females carry only 3 to 8 or 10 eggs at a time, with ripe eggs at least 0.5 mm in diameter and relatively large for the fish's body size, indicating small, frequent spawns rather than large batches.

Sexing

The body is so transparent that ripe females can be distinguished by the relatively large eggs (about 0.3-0.6 mm, ripe at least 0.5 mm) visible within the body cavity (Wikipedia). Males lack this visible egg mass.

Conditioning

As a micro-predator in the wild this species takes small live foods; conditioning on tiny live and frozen items supports the continuous production of its small egg clutches. Keep a group, as the species naturally occurs in numbers among plant roots.

Breeding Setup

• Mature, gently filtered nano tank with very calm water, mirroring the slow-flowing shallow habitat (Wikipedia).
• Fine substrate or dense fine-leaved plants and moss so the small eggs settle out of reach.
• Soft to moderate, near-neutral water; the keeping record gives 22-27 C, pH 6.5-7.5 and 4-12 dGH.
• Stable conditions for continuous low-volume spawning rather than a single large event.

Spawning Behavior & Trigger

Because females carry only a handful of eggs at any time (3 to 8 or 10), the species spawns small numbers continuously when held in a settled group in stable water, depositing eggs among fine substrate and plant roots rather than in one large scattering (Wikipedia).

Egg & Fry Care

The eggs are large relative to the adult yet still minute, and the resulting fry are correspondingly tiny, so the smallest possible live foods are required at first. The transparent biology that makes the genus a neuroscience model also makes egg and fry losses easy to overlook, so a separate, undisturbed grow-out is advised.

Common Challenges

The extreme small size and fragility of both adults and fry, plus the very small clutch, make population build-up slow. Detailed aquarium spawning protocols are limited in the literature, so the species is best treated as an advanced project relying on stable water and a permanent group.