Glass Tetra (Moenkhausia oligolepis) Breeding Guide

Breeding Moenkhausia oligolepis, a prolific egg-scatterer: cool, soft, acidic water, fine-plant spawning sites and eggs that hatch in 24-36 hours.

Overview

Moenkhausia oligolepis, the glass or redeye tetra, ranges throughout much of northern South America, including Venezuela, Guyana, Suriname, French Guiana, Peru and Brazil. FishBase describes the species as oviparous, very prolific and very easy to breed in the aquarium. It is an egg-scatterer that provides no parental care.

Sexing

Adult females tend to be fuller-bodied than males, the difference being most obvious when females are carrying eggs.

Conditioning

Two approaches are used. For group spawning, condition about half a dozen of each sex together on live foods. For pair spawning, condition the sexes separately, then move the heaviest female and best-coloured male to the breeding tank in the evening; spawning usually follows the next morning.

Breeding Setup

• Spawning tank around 18 x 10 x 10 inches, kept very dimly lit.
• Soft, acidic water: pH 6.0-7.0 and hardness around 1-10 gH.
• Temperature approximately 22-24 C (72-76 F).
• Fine-leaved plants such as java moss or spawning mops, or a mesh base allowing eggs to fall through.
• A gently bubbling air-powered sponge filter.

Spawning Behavior & Trigger

Eggs are scattered among plants or fall through protective mesh. Soft acidic water and subdued lighting are the main triggers. As a very prolific species the female can produce many eggs, but the adults will eat them and should be removed immediately once spawning is complete.

Egg & Fry Care

Eggs hatch in 24-36 hours, and the fry become free-swimming about 3-4 days later. Start the free-swimming fry on infusoria-type foods, progressing to microworm or brine shrimp nauplii as they grow.