Breeding Corydoras gracilis (Slender Cory)

Breeding guide for the dwarf Corydoras gracilis: sexing, conditioning, the cool soft-water spawning trigger and demanding fry care.

Overview

Corydoras gracilis is a dwarf armoured catfish (family Callichthyidae) from the central Amazon basin in northwestern Brazil, reaching about 30–40 mm. It is an egg-depositor that spawns in the Corydoras T-position and can be bred in a tank with a base footprint from about 60 × 30 cm.

Sexing

Females tend to grow larger, and sexually mature individuals are noticeably broader and deeper-bodied than males, most obvious from above when females are full of eggs.

Conditioning

Condition adults on a varied diet of small live and frozen foods until the females are visibly full of eggs. Use a ratio of two or more males per female if possible.

Breeding Setup

• Temperature: 20–26 °C
• pH: 5.0–7.5
• Hardness: 36–215 ppm
• Provide glass, fine-leaved plants and/or sunken spawning mops; mops are recommended because they facilitate easy egg removal

Spawning Behavior & Trigger

When the females are visibly full of eggs, perform a large (50–70%) water change with cooler water and increase oxygenation and flow in the tank. 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, fine-leaved vegetation or a mop.

Egg & Fry Care

Incubation is normally 3–4 days. Once the fry have fully absorbed their yolk sacs they accept small live foods such as microworm and Artemia nauplii. They are not the easiest to raise, requiring excellent water quality, but seem less susceptible to ailments when maintained over a thin layer of sand rather than in a bare arrangement.

Common Challenges

Fungus prevention involves adding a few drops of methylene blue or an alder cone or two to the egg container.