Breeding Corydoras delphax (False Blochi Cory)

Breeding guide for Corydoras delphax: sexing, conditioning, the cool soft-water spawning trigger, T-position mating and fry care.

Overview

Corydoras delphax is an armoured catfish (family Callichthyidae) from the upper Orinoco basins in western Colombia and northeastern Peru, reaching about 55–60 mm. It is an egg-depositor that spawns in the typical Corydoras T-position.

Sexing

Females tend to grow larger, and sexually mature individuals are noticeably rounder and higher-bodied than males, especially when full of eggs and viewed from above.

Conditioning

Condition adults on a varied diet of small live and frozen foods until females are full of eggs. Use a ratio of two males per female if possible to maximise fertilisation.

Breeding Setup

• Temperature: 22–27 °C
• pH: 5.5–7.5
• Hardness: 36–215 ppm
• Provide glass, fine-leaved plants and/or sunken spawning mops; mops make egg removal easy

Spawning Behavior & Trigger

Trigger spawning by performing a large (50–70%) water change with cooler water and increasing oxygenation and flow. Repeat daily until the fish spawn. The female cups the sticky eggs between her pelvic fins, fertilises them in the T-position, and deposits them on glass, vegetation or a mop.

Egg & Fry Care

Incubation is normally 3–4 days. Once the yolk sacs are absorbed, fry accept small live foods such as microworm and Artemia nauplii. They require excellent water quality and perform better over a thin layer of sand than on a bare bottom.

Common Challenges

To prevent egg fungus, breeders typically add a few drops of methylene blue or an alder cone or two to the egg container.