Corydoras robustus Breeding Guide

Breeding the Robust Cory (Corydoras robustus): sexing, conditioning, water-change trigger, T-position spawning and fry care for this larger species.

Overview

Corydoras robustus is one of the larger members of the genus, reaching about 9.5 cm, and is endemic to the Rio Purus drainage in Brazil. It is an egg-depositing catfish that spawns in the genus's typical T-position; its size means it needs more space than most corys both for maintenance and for a breeding group.

Sexing

Seriously Fish reports that females are noticeably rounder and broader-bodied than males, especially when full of eggs, and that males have more extended first dorsal-fin rays.

Conditioning

Condition the group on a varied diet of live, frozen and dried foods. Seriously Fish recommends a 2:1 male-to-female ratio.

Breeding Setup

Seriously Fish suggests a tank of at least 18 by 12 by 12 inches with a bare bottom, sand or fine gravel, sponge or box filtration and Java moss. Target around 24 degrees C (75 F) and pH 6.5; filtering through peat and using RO water are beneficial. Maintenance parameters are 22-26 degrees C, pH 6.0-7.0 and hardness 1-12 dH.

Spawning Behavior & Trigger

Trigger spawning with a large 50-70% water change using cooler water and increased oxygenation, repeated daily until the fish reproduce. In the T-position the male grasps the female's barbels; she forms a pelvic-fin basket and deposits a single egg at a time (although up to four may be released at once), attaching the eggs in repeated cycles.

Egg & Fry Care

Seriously Fish gives a hatch time of 3-5 days. Once the fry have absorbed their yolk sacs they accept microworm and brine shrimp nauplii, and develop better over a thin layer of sand than in a bare-bottomed setup.

Common Challenges

As the largest species in this group, robustus needs a roomy spawning tank and strong oxygenation to bring a heavy female into condition. Fungused eggs and declining water quality are the most common causes of losses.