Corydoras Catfish at a Glance
Corydoras are among the most beginner-friendly freshwater fish — they add activity, personality, and utility to almost any peaceful tank.
Corydoras Size & Activity
Corydoras Species Comparison
| Species | Max Size | Min Tank | Temp °F | pH Range | Activity Level |
|---|---|---|---|---|---|
| Bronze (C. aeneus) | 2.5" | 20 gal | 72-78 | 6.0-8.0 | Very active |
| Panda (C. panda) | 2" | 20 gal | 68-77 | 6.0-7.5 | Moderate |
| Sterbai (C. sterbai) | 2.5" | 20 gal | 74-82 | 6.0-7.5 | Active |
| Pygmy (C. pygmaeus) | 1" | 10 gal | 72-78 | 6.0-7.5 | Midwater swimmer |
| Peppered (C. paleatus) | 3" | 20 gal | 68-78 | 6.0-7.5 | Active |
| Skunk (C. arcuatus) | 2" | 20 gal | 72-78 | 6.0-7.5 | Active |
Corydoras Care Rules
| Provide soft sand substrate — essential for barbel health | |
| Keep groups of 6+ of the same species for natural schooling behavior | |
| Offer sinking pellets and frozen foods (bloodworms, brine shrimp) | |
| Include hiding spots (caves, driftwood, plant cover) | |
| Perform regular gravel vacuuming to keep substrate clean | |
| Use sharp gravel — it erodes barbels and causes infections | |
| Keep alone or in pairs — corys are shoaling and need groups | |
| Add to uncycled tanks — they're sensitive to ammonia/nitrite | |
| Keep with large aggressive fish that will outcompete them for food |
Corydoras barbels are sensory organs, not whiskers. Damaged or missing barbels indicate poor substrate or water quality — fix the cause, not the symptom.
Pygmy corys (Corydoras pygmaeus) are unique among corys — they swim in the midwater, not just the bottom, and do well in smaller planted tanks from 10 gallons.
Corydoras catfish are small, armored bottom-dwellers from South American rivers that are genuinely beginner-friendly, useful in community tanks, and interesting enough to build a dedicated collection around. Over 160 species have been described, ranging from the 1-inch pygmy cory to the 3-inch emerald cory, all sharing the characteristic spine-protected body, barbels for substrate sensing, and social nature. Corydoras kept in groups of 6+ are visibly more active and behaviorally engaging than those kept singly or in pairs.
| Species | Size | Temp Preference | Notes |
|---|---|---|---|
| C. paleatus / C. aeneus | 2–3 in | 72–78°F | Most forgiving; best beginners |
| C. sterbai | 2.5 in | 78–82°F | Warm-water; compatible with discus |
| Pygmy corys (C. pygmaeus) | 1 in | 72–79°F | Mid-water schoolers; group 10+ |
| C. panda (Panda cory) | 1.5 in | 68–75°F | Cooler water preference; distinctive eye patch |
Why They Need Groups
Corydoras are schooling fish that move, forage, and rest together in the wild. A single cory will survive but will spend most of its time hiding, moving minimally, and displaying a fraction of its natural behavior. In groups of 6+, they become a constant presence: zipping to the surface for a gulp of air (they supplement gill respiration with intestinal air-breathing), foraging together across the substrate, and displaying distinct social behaviors including spawning dances. Groups of 10-12 corydoras in a well-set-up tank are one of the most engaging experiences in the freshwater hobby.
Common Species and Their Differences
Corydoras paleatus (peppered cory) and C. aeneus (bronze cory) are the most widely available and most forgiving of water parameters. C. sterbai is a popular mid-sized species with orange pectoral fins and white spots on a dark body -- it prefers slightly warmer water (78-82F) than most species, making it compatible with discus tanks. Pygmy corydoras (C. pygmaeus, C. habrosus) are tiny (under 1 inch) and spend more time in the water column than on the bottom. Panda corydoras (C. panda) have distinctive black eyepatch markings and do best in cooler water (68-75F). Species should be kept with their own species for proper shoaling behavior.
Water Parameters
Most Corydoras species tolerate a wide range: pH 6.0-8.0, hardness 2-20 dGH, temperature 72-78F for most temperate species (adjust for species-specific requirements). The critical factors: excellent water quality and soft substrate. Corydoras use sensitive barbels to search for food in substrate -- coarse gravel abrades these and causes progressive barbel erosion, eventually impairing the fish's ability to feed. Fine sand (pool filter sand, black diamond blasting sand) or smooth fine gravel is the appropriate substrate.
Feeding
Corydoras are omnivorous bottom scavengers. Sinking wafers (Hikari Sinking Wafers, New Life Spectrum Bottom Feeder) are the primary food; supplement with frozen bloodworms, daphnia, and brine shrimp. Feed at lights-out when Corydoras are most active and less likely to be beaten to food by surface feeders. They do not subsist on algae or leftover food from other fish -- this is a myth that leads to slow starvation when corydoras are not intentionally fed.
Tank Compatibility
Corydoras are peaceful with virtually any community fish that doesn't eat them (no large cichlids, predatory catfish, or fish large enough to consume an adult cory). Avoid any fish with a history of sucking on other fish (certain plecos, Chinese algae eaters) -- their behavior injures corydoras. The Corydoras spine defense means predators that swallow them can be fatally injured -- this protects corydoras in most situations but is an important fact for anyone feeding them to aggressive fish or predatory species.
Sources: Seriously Fish Corydoras species profiles; Fuller I -- "Corydoras Catfish: The Most Popular Catfishes of the Aquarium" (academic reference); Callichthyidae family taxonomy (Ferraris, 2007); Amazonas Magazine community tank guides.