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.

Temperature: Identify the species before using this broad temperature range; approximately 72-79°F (22-26°C) suits many common species. Some prefer cooler water, while warm-tolerant species such as Sterba's cory are better choices for warmer communities.

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.

Difficulty: Easy to moderate, depending on species. They need a mature, fully cycled aquarium, a social group, smooth substrate, appropriate temperature, and food that reaches the bottom.

Minimum Tank: 20 gallons for a group of most common small-to-medium species; a 20-gallon-long or larger aquarium is preferred. Dwarf species may suit a carefully planned 10-15 gallon tank, while larger species require more room.

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.

Compatibility

Good Tank Mates: Peaceful tetras, rasboras, pencilfish, small danios with matching temperature needs, hatchetfish, peaceful gouramis, small livebearers, Otocinclus, kuhli loaches, peaceful dwarf cichlids with adequate space, adult shrimp, and snails.

Use Caution With: Territorial bottom dwellers, food-aggressive fish, fin-nippers, large plecos, crayfish, and warm-water species if the selected cory prefers cooler conditions.

Avoid: Large predatory fish, aggressive cichlids, fish capable of swallowing them, and tank mates that consistently prevent them from feeding.

Compatibility Notes: Corydoras are not effective algae eaters and should never be expected to survive on waste or leftovers. They may eat eggs, tiny fry, or very small invertebrates they encounter, but they do not normally hunt healthy community fish.

Feeding

Captive Diet: A varied diet of quality sinking foods supplemented with frozen or live foods.

Recommended Foods: Sinking catfish pellets, quality wafers, frozen or live bloodworms, daphnia, brine shrimp, cyclops, blackworms from a safe source, and occasional gel or vegetable-containing foods.

Feeding Frequency: Feed 1-2 small portions daily, adjusting the amount so the group eats well without leaving food to decay.

Feeding Behavior: Uses barbels and taste receptors to locate food and may bury the snout while sifting sand. Food should be distributed across several bottom areas so every fish can eat.

Special Requirements: Target-feed sinking food after faster midwater fish have taken their portion. Check that shy or newly introduced fish have rounded, well-filled bodies rather than sunken bellies.

Health

Signs of Stress: Rapid or labored breathing, persistent surface gasping, clamped fins, loss of appetite, lethargy, redness, damaged or shortened barbels, white spots, abnormal swelling, sunken belly, isolation, or loss of balance.

Common Keeper Mistakes: Keeping one or two fish, mixing singles of several species instead of forming a proper group, using sharp substrate, treating them as scavengers, choosing an unsuitable temperature, adding them to an uncycled tank, and housing them with aggressive or food-competitive fish.

Initial Checks: For reduced feeding, barbel injury or repeated rapid breathing, inspect substrate, access to sinking food and measured water conditions. Record recent maintenance and additions and seek qualified fish-health advice; an occasional surface visit alone does not identify disease.

Suitability

Important Things Before Buying: Identify the exact species rather than buying an unlabeled 'assorted cory.' Confirm adult size and temperature needs, plan for at least 6 matching fish, and prepare a cycled tank with fine sand. Choose alert fish with intact barbels, clear skin, normal breathing, and full bellies; quarantine when possible.