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Corydoras are one of the most compatible community fish in the freshwater hobby. They are peaceful, occupy the bottom of the tank, and do not compete with mid-water or surface-dwelling species for space or food. Their main vulnerability is their small size and bottom-dwelling nature — large or aggressive fish can harass or eat them. This guide covers the best tankmates for corydoras, what to avoid, and how to build a successful community tank around them.
The Ground Rules
- Corydoras occupy the bottom: They are most compatible with fish that occupy different parts of the water column. Mid-water and surface-dwelling species rarely compete with corydoras for space or food.
- Size matters: Corydoras are small to medium-sized fish. Large fish that could fit a corydoras in their mouth are a risk, even if generally considered peaceful.
- Substrate is shared: Bottom-dwelling fish that compete for the same territory or food can stress corydoras. Research any other bottom dwellers before combining them.
- Keep the school intact: Corydoras need a group of at least 6 of the same species. Adding too many other species at the expense of school size increases stress.
- Tank size: A 20-gallon minimum for corydoras alone; 30+ gallons for a community setup with multiple species.
Good Corydoras Tankmates
Tetras
Most small, peaceful tetras are among the best corydoras tankmates. They occupy the mid-water column, share compatible water parameters, and are completely non-aggressive toward bottom dwellers. Neon tetras, cardinal tetras, rummy nose tetras, ember tetras, and glowlight tetras all work well. Avoid large or fin-nipping tetra species like serpae tetras or Buenos Aires tetras.
Rasboras
Harlequin rasboras, chili rasboras, and lambchop rasboras are peaceful schooling fish that coexist well with corydoras. They prefer similar water parameters and occupy the mid-water column, leaving the bottom to the corydoras.
Guppies and Small Livebearers
Guppies, platies, endlers, and mollies are generally compatible with corydoras. They occupy the upper water column and are non-aggressive. Water parameter overlap is worth checking — corydoras prefer slightly softer, more acidic water than most livebearers, but in tanks with neutral pH and moderate hardness both can coexist comfortably.
Dwarf Gouramis
Dwarf gouramis are generally compatible with corydoras in tanks of 30 gallons or more. They occupy the upper water column and rarely interact with bottom-dwelling corydoras. Individual temperament varies — monitor for any aggression during the first few days after introduction.
Bettas (With Caution)
Bettas and corydoras can coexist in well-planted tanks of 20 gallons or more. Corydoras occupy the bottom and bettas the upper column, which reduces direct competition. Some bettas ignore corydoras entirely; others may nip at them. This combination works best in larger tanks with plenty of cover and is not recommended for beginners.
Otocinclus
Otocinclus are small, peaceful algae eaters that share the bottom and glass surfaces with corydoras without conflict. Both species are non-aggressive and have compatible water parameter requirements. They make a practical pairing in planted tanks.
Other Corydoras Species
Different corydoras species can be kept together in the same tank. They may interact peacefully and will share the bottom without conflict. However, corydoras show the strongest schooling behavior with members of their own species — a mixed group of two species is less cohesive than two separate same-species schools. If keeping multiple species, maintain a group of at least 6 of each.
Snails and Shrimp
Nerite snails, mystery snails, and Amano shrimp are compatible with corydoras. Corydoras generally ignore invertebrates. Cherry shrimp can coexist with corydoras in planted tanks, though very small shrimplets may occasionally be eaten. Adult cherry shrimp are typically left alone.
Tankmates to Avoid
Large Cichlids
Most cichlids are too large or aggressive for corydoras community tanks. Even cichlids marketed as peaceful — such as some South American species — can become territorial and harass or injure corydoras. Research carefully before combining any cichlid with corydoras.
Goldfish
Goldfish require cooler temperatures than most corydoras species (with the exception of peppered corys). They also produce significantly more waste, which can compromise the water quality corydoras need. Large goldfish may eat smaller corydoras, particularly juvenile or pygmy species. Avoid this combination except with peppered corys in cool-water setups, and even then monitor carefully.
Aggressive Bottom Dwellers
Fish that compete for the same bottom territory can stress corydoras. Some larger loaches, aggressive plecos, and territorial catfish may harass corydoras over food or space. Not every loach is a problem — smaller, peaceful species like kuhli loaches are generally fine — but research any bottom-dwelling species carefully before combining them with corydoras.
Large Predatory Fish
Any fish large enough to fit a corydoras in its mouth is a potential predator. This includes many commonly kept fish that are sold as community species. When in doubt, research the adult size and feeding behavior of any potential tankmate before adding it to a corydoras tank.
How to Introduce Tankmates
- Ensure the tank is large enough for both corydoras and new tankmates before adding anything
- Quarantine new fish for 2–4 weeks before adding them to the main tank
- Observe closely during the first 48–72 hours for chasing, nipping, or stress behavior
- Ensure corydoras are receiving their own sinking food — faster mid-water feeders will not leave food for bottom dwellers