Corydoras Catfish

A 10 to 20 gallon tank suits a proper school, since corydoras are obligate shoaling fish that need at least six of the same species to feel secure. Soft sand substrate is essential — sharp or rough gravel damages their sensitive barbels, the whisker-like feelers they use to find food. Gentle filtration, driftwood, and plants for cover round out a good setup, kept at 72 to 78 degrees F with well-oxygenated water.

Corydoras are omnivorous bottom feeders that do best on sinking wafers or pellets formulated specifically for catfish. Supplement with blanched vegetables and frozen bloodworms or brine shrimp for variety. Feed in the evening, or make sure food reaches the bottom before faster mid-water fish eat it all — relying only on leftover flake food from other tankmates does not provide adequate nutrition for corydoras.

Corydoras must be kept in groups of six or more of the same species; solitary or small-group individuals show visible stress and reduced activity compared to a properly sized school. They spend much of the day actively foraging, sifting through soft substrate with their barbels, and displaying playful, synchronized schooling behavior. Periodic surface dashes for air are a natural and healthy part of their routine. They also appreciate caves and plant cover to retreat to when resting.

Barbel damage or erosion from sharp or rough substrate is a very common and entirely preventable problem — always use sand or smooth, fine gravel. Ich and bacterial infections both follow poor water quality. Corydoras are also sensitive to some medications, since many contain copper, which is toxic to scaleless catfish, so always check a treatment's corydoras-safety before dosing the tank. Because they spend their time along the bottom, they're often the first fish affected by settling waste, making regular gravel vacuuming and 20 to 25 percent weekly water changes especially important.