Corydoras Catfish

Habitat

Natural Habitat: Species occupy shallow streams, tributaries, floodplains, pools, wetlands, and river margins. Bottoms may consist of sand, fine sediment, leaf litter, roots, and submerged vegetation, with flow ranging from nearly still to moderate.

Natural Water Conditions: Highly variable by species and season. Many habitats are soft and slightly acidic to neutral, but some species occur in clearer, harder, cooler, warmer, or more strongly flowing water.

Other Habitat Notes: Seasonal rain and flooding can change temperature, depth, current, food availability, and water chemistry. Corydoras use sensitive barbels to search the bottom and can breathe atmospheric air through a specialized intestine.

Aquarium

Tank Size Notes: Bottom area matters more than height. A long aquarium provides more feeding and foraging space and supports a larger social group.

Tank Shape: A long, standard rectangular aquarium with generous floor area

Substrate: Fine, smooth sand is strongly preferred because it supports natural sifting and protects the barbels and mouth. Very smooth, rounded fine gravel can work, but avoid sharp or coarse material.

Plants: Live plants are beneficial but not required. Rooted plants, epiphytes, mosses, and floating plants create shade and security while leaving open substrate for foraging.

Hardscape: Smooth driftwood, rounded stones, leaf litter where appropriate, and stable caves or shaded overhangs

Hiding Places: Provide shaded retreats and planted edges, but do not overcrowd the entire bottom; the group also needs open sand for feeding and social activity.

Swimming Space: Maintain broad, unobstructed bottom areas and enough open water for brief dashes to the surface.

Water Flow: Gentle to moderate with good oxygenation for most species; match flow to the species and provide calmer resting areas.

Lighting: Low to moderate. Shade from plants or wood helps them feel secure.

Lid Required: Recommended. Corydoras make quick trips to the surface and can jump or leave an uncovered aquarium when startled.

Other Setup Notes: Keep ammonia and nitrite at 0 ppm and nitrate controlled through maintenance. Leave clear access to the surface for air gulping, protect filter intakes, and avoid decorations with sharp edges or narrow traps.

Behavior

General Behavior: Active social foragers that nose through sand, rest together, and make brief trips to the surface for air. Activity often increases around feeding time and after water changes.

Aggression: Very low. Harmless jostling may occur during feeding or courtship.

Territorial: No

Schooling/Social Behavior: They form loose shoals rather than maintaining a tight school. A sufficiently large same-species group makes them more confident and allows natural resting, feeding, and courtship behavior.

Group Requirements: Keep at least 6 of the same species. Different cory species may associate, but a mixed collection of single fish does not fully replace a proper same-species group.

Notable Behaviors: Occasional rapid surface trips and an immediate return to the bottom are normal air-breathing behavior. Repeated gasping, lingering at the surface, rapid gill movement, or a sudden increase across the group can indicate low oxygen, poor water quality, excessive heat, or illness.