What Bandit Corydoras Are and Where They Come From

Bandit corydoras are small bottom-dwelling catfish native to South America, primarily the Amazon and Orinoco river basins. They reach about 1 to 1.5 inches in length and are named for the dark stripe running across their eyes, which resembles a bandit's mask. Unlike many corydoras species, bandits are somewhat more aggressive and territorial than their cousins, particularly toward each other and toward other bottom feeders.

In the wild, bandit corydoras inhabit slow-moving streams and tributaries with sandy or muddy substrates, dense vegetation, and plenty of leaf litter. They are schooling fish that naturally live in groups, though they are less peaceful in groups than other corydoras species. Their behavior in captivity reflects this: they will establish dominance hierarchies and may chase or nip at tank mates, especially during feeding or when defending territory.

Key Takeaways

  • Bandit corydoras require a minimum 20-gallon tank with sand substrate, as they dig constantly and can injure themselves on gravel.
  • They are schooling fish and should be kept in groups of at least 4 to 6, though they are more aggressive toward each other than other corydoras species.
  • Water temperature should stay between 72 and 82 degrees Fahrenheit, with weekly water changes of 25 percent to maintain water quality.
  • They are bottom feeders but do not clean the tank on their own; they require sinking pellets, algae wafers, and occasional live or frozen foods.
  • Breeding in captivity is possible but requires cooler water (around 68 to 70 degrees) and a separate breeding tank to protect eggs and fry.

Tank Size and Substrate Requirements

A single bandit corydoras needs a minimum of 10 gallons, but because they are schooling fish and should be kept in groups, a 20-gallon long tank is the practical starting point for 4 to 6 individuals. Larger groups benefit from 30 gallons or more. Tank length matters more than height, since these fish spend nearly all their time on the bottom and rarely venture into the upper water column.

Sand substrate is non-negotiable for bandit corydoras. They dig constantly, sifting through the bottom in search of food and creating burrows. Gravel will damage their delicate barbels (whisker-like sensory organs around their mouth) and can cause infections. Use aquarium sand, pool filter sand, or play sand that has been thoroughly rinsed. Avoid sand with sharp edges or added chemicals.

Provide hiding places with driftwood, PVC pipes, or dense plants. Bandit corydoras are nocturnal and spend much of the day in shelter. They are also more likely to dig and hide when stressed, so adequate cover reduces aggression within the group and makes the fish feel secure enough to forage openly during low-light hours.

Water Conditions and Tank Maintenance

Bandit corydoras thrive in warm, slightly acidic to neutral water. Keep the temperature between 72 and 82 degrees Fahrenheit, with 75 to 78 degrees being ideal for most community setups. pH should range from 6.0 to 7.0, and hardness between 2 and 12 dGH. They are sensitive to ammonia and nitrite, so a cycled tank is essential before adding any fish.

Perform a 25 percent water change every week. Because bandit corydoras dig and stir the substrate, they disturb detritus and increase the bioload in the tank. Weekly changes prevent the accumulation of waste that would otherwise spike ammonia and nitrite levels. Use a gravel vacuum to remove debris from the sand surface without pulling up the sand itself.

A sponge filter or gentle hang-on-back filter works well, as bandit corydoras prefer low to moderate water flow. Strong currents stress them and make it harder for them to forage. If using a canister filter, reduce the outlet flow with a spray bar or by adjusting the valve. Avoid powerheads or strong aeration directly over the substrate.

Feeding and Diet

Bandit corydoras are omnivorous bottom feeders, but they do not survive on algae and leftover food alone. They require a varied diet of sinking foods, as they cannot compete with faster fish at the surface. Feed high-quality sinking pellets designed for corydoras or bottom feeders as the staple, supplemented with algae wafers two to three times per week.

Offer live or frozen foods once or twice weekly to maintain health and encourage natural foraging behavior. Bloodworms, brine shrimp, daphnia, and small earthworms are all accepted readily. These foods also help condition fish for breeding. Feed in the evening or at night when the corydoras are most active, and remove any uneaten food after a few hours to prevent water quality problems.

Do not rely on bandit corydoras to clean the tank. They will eat some algae and detritus, but they are primarily scavengers that eat what is offered to them. Overfeeding is common when people assume the corydoras will consume excess food; instead, uneaten food decays and fouls the water. Feed only what the fish will consume in 2 to 3 minutes.

Temperament and Tank Mates

Bandit corydoras are more aggressive than other corydoras species, particularly toward each other. Males will chase and nip at rivals, and dominant individuals may prevent subordinates from feeding. Keeping them in groups of 4 to 6 spreads aggression across multiple individuals and reduces the chance that one fish will be singled out and harassed. A larger tank with plenty of hiding places also helps.

They coexist with peaceful community fish such as tetras, rasboras, dwarf gouramis, and small peaceful plecos. Avoid housing them with aggressive fish, large cichlids, or other bottom feeders that will compete for food and space. They may also nip at slow-moving fish with long fins, such as bettas or fancy goldfish. Do not mix bandit corydoras with other corydoras species, as they will harass them relentlessly.

Bandit corydoras should never be kept alone. A solitary individual will become stressed and may hide constantly or develop aggressive behavior toward other fish. They are social within their own species, even if that sociality includes some conflict, and they are most active and healthy when kept in a proper group.

Breeding Bandit Corydoras in Captivity

Breeding bandit corydoras is possible but requires patience and a separate breeding tank. Condition the group with frequent live food for 2 to 4 weeks, then move a male and female (or a small group) to a 10 to 15-gallon breeding tank filled with sand, plants, and hiding places. Lower the temperature to 68 to 70 degrees Fahrenheit and perform daily 50 percent water changes with slightly cooler water to simulate the rainy season.

Spawning typically occurs in the early morning. The female will lay small clusters of eggs on plants, driftwood, or the tank glass, and the male will fertilize them. Remove the adults immediately after spawning, as they will eat the eggs. Eggs hatch in 3 to 5 days, and fry become free-swimming 5 to 7 days later. Feed fry infusoria or liquid fry food for the first week, then transition to newly hatched brine shrimp and finely crushed flake food.

Raising fry to adulthood requires frequent small water changes and careful feeding to maintain water quality. Many hobbyists find breeding bandit corydoras rewarding but time-intensive. Fry grow slowly and do not reach adult size until 4 to 6 months of age.

Common Health Issues and Prevention

Bandit corydoras are hardy fish when kept in proper conditions, but they are susceptible to several common problems. Barbel erosion occurs when fish are kept on gravel or in poor water quality; it appears as shortened or missing barbels and is often irreversible. Sand substrate and regular water changes prevent this condition entirely.

Ich (white spot disease) and fin rot are common in tanks with poor water quality or temperature fluctuations. Maintain stable conditions and perform regular water changes to prevent these infections. If disease appears, treat with salt baths or medication designed for catfish, as some corydoras are sensitive to certain medications. Always check the label before treating.

Stress from overcrowding, aggressive tank mates, or inadequate hiding places can lead to loss of appetite and disease. Ensure the tank is large enough for the group, provide plenty of shelter, and monitor feeding behavior daily. A bandit corydoras that stops eating or hides constantly is signaling a problem that needs immediate attention.

Frequently Asked Questions

Can bandit corydoras live with other corydoras species?

No. Bandit corydoras are significantly more aggressive than other corydoras species and will chase, nip, and harass other corydoras relentlessly. Keep them only with their own kind, and provide a large tank with plenty of hiding places to reduce conflict within the group.

How many bandit corydoras should I keep together?

Keep at least 4 to 6 individuals together. A group of this size spreads aggression across multiple fish and reduces the likelihood that one individual will be singled out and bullied. Larger groups in bigger tanks are even better, as more space and hiding places reduce stress.

Do bandit corydoras need a heater?

Yes, unless your room temperature stays consistently between 72 and 82 degrees Fahrenheit. Most home aquariums require a heater to maintain the warm water these fish need. Use a reliable aquarium heater with a thermostat to prevent temperature swings, which stress the fish and promote disease.

What size tank do I need for 6 bandit corydoras?

A 20-gallon long tank is the minimum for 6 individuals, though a 30-gallon or larger tank is better. Tank length matters more than height, since these fish live on the bottom. A 20-gallon long (30 inches by 12 inches) provides more usable bottom space than a 20-gallon tall (24 inches by 12 inches by 16 inches high).

Will bandit corydoras eat my plants?

Bandit corydoras do not eat live plants, but they will dig around and uproot them while foraging. Use hardy, well-rooted plants such as anubias or java fern, or plant them in pots to protect the roots. Soft, delicate plants are likely to be uprooted and damaged.