Corydoras acutus Breeding Guide

How to breed the Blacktop Corydoras (Corydoras acutus): sexing, conditioning, the cooler-water spawning trigger, T-position pairing and fry care, based on the documented genus pattern.

Overview

Corydoras acutus, the blacktop cory, is a pointed-snouted armoured catfish reaching about 65-70 mm standard length. It occurs across parts of the upper Amazon basin in Brazil, Peru, Ecuador and possibly Bolivia, including the rios Yavari, Abuna (Madeira system), Nueva Rocafuerte (Napo system) and Huitoyacu (Maranon system) (Seriously Fish). It is a peaceful egg-depositor. Species-specific spawning data are not documented, so the procedure below follows the genus pattern; treat figures as approximate.

Sexing

Females grow larger and become noticeably rounder and broader-bodied than males when sexually mature, especially when gravid (Seriously Fish). The fuller female body is most apparent from above.

Conditioning

The species is a foraging omnivore that takes sinking dried foods, bloodworm and Tubifex; it requires a varied diet and should not rely on tank leftovers (Seriously Fish). Conditioning females on rich live and frozen foods over several weeks builds them into full spawning condition, at which point they fill visibly with eggs when viewed from above.

Breeding Setup

Provide a separate tank with fine sand or a bare base, gentle sponge filtration and fine-leaved plants or spawning mops. As a pointed-snouted, bottom-sifting cory, it needs soft sand to protect its delicate barbels. Hold the water within the tolerated range of pH 6.0-7.5 and roughly 22-28 degrees C (Seriously Fish), keeping it clean and well-oxygenated.

Spawning Behavior & Trigger

Genus spawning is prompted by a large (50-70%) cooler water change with increased oxygenation and flow, repeated daily until the fish respond; this simulates rainy-season conditions. Pairs assume the T-position, the female holding eggs in a pelvic-fin basket while collecting milt, then attaching sticky eggs to glass, leaves or a mop. She repeats the process in successive passes through a spawning session. Precise egg counts for C. acutus are not recorded in the consulted sources.

Egg & Fry Care

Adults eat their eggs, so separate parents or eggs after spawning. Genus eggs hatch in about 3-5 days; free-swimming fry take microworm and newly hatched brine shrimp once their yolk sacs are absorbed. Maintain excellent water quality throughout rearing, ideally over a thin sand layer with frequent small water changes.

Common Challenges

Conditioning, a reliable cool-change trigger and egg predation are the principal hurdles. Infertile-egg fungus and unstable water during the fry phase cause most losses, so close attention to hygiene during the egg and early fry stages is essential.