Best Corydoras Tank Mates

What makes a good tank mate for corydoras?

A good corydoras tank mate is a peaceful fish that is too small to eat a cory, shares its water and leaves the bottom of the tank to the catfish. Corydoras are small armoured catfish from South America; the reference species on this page is the bronze cory (Corydoras aeneus), which Dias et al. (2024) moved to Osteogaster aenea but which is still sold under its old name. Aquarium Co-Op sums up the rule in one line: corys suit nearly any community fish that will not eat or attack them. Four criteria follow from the published data.

1. Too small to eat a cory. The bronze cory grows to 3 in (7.6 cm). Aquarium Co-Op warns that corys are eaten by goldfish and by any tank mate large enough to attack them, so predators and large omnivores rule themselves out.
2. Peaceful at the bottom. PlanetCatfish calls the bronze cory a perfect citizen for community tanks, and it does not defend territory. Tank mates that guard the substrate, such as male bristlenose plecos with caves, need enough floor space for both.
3. Moderate shared water. Corydoras need 70–81 °F (21–27 °C), pH 6.5–7.5 and 2–15 dGH. That middle band overlaps most community fish but excludes coldwater goldfish and very warm-water discus.
4. Food that reaches the floor. Seriously Fish describes corys as foraging omnivores that take sinking foods. Fast mid-water fish do not compete with them directly, which is why schooling tetras and rasboras top the list below.

Swim level is the easiest criterion to meet. Corydoras are bottom dwellers, so any upper or mid-water schooling fish adds activity without crowding them. The same logic drives the other pages in our tank mates by species series, and the species compatibility checker scores any pairing not listed here.

Which fish are the best corydoras tank mates?

The best corydoras tank mates are small schooling fish that swim above them in the same soft-to-moderate water. The groups below follow the order of the table.

Neon tetra and harlequin rasbora

The neon tetra scores 10/10 and the harlequin rasbora 10/10. Both are peaceful mid-water schoolers, and their pH ranges contain the cory’s, so the pair shares the cory’s full pH 6.5–7.5. Seriously Fish lists small catfish among the neon tetra’s suitable companions, and our harlequin data names catfish and loaches among the groups it suits. The neon needs a school of 8, as does the harlequin, so a tank holding both schools and six corys is a planned community rather than a nano tank.

Cardinal tetra, zebra danio and GloFish tetra

The cardinal tetra scores 9/10. It needs warmer water than the neon, so the pair shares 73–81 °F (23–27 °C) rather than the cory’s full range. Zebra danios score 9/10 but sit at the cool end, sharing only 70–75 °F (21–24 °C). GloFish tetras score 9/10; their fin-nipping reputation, which Seriously Fish attributes to the black tetra they are bred from, matters for long-finned fish but not for a short-finned catfish.

Guppies, platies, mollies and Endler’s livebearers

Livebearers score well on temperament but lose points on water chemistry, because they prefer harder, more alkaline water than corys. Guppies score 9/10 and share pH 7.0–7.5; platies score 8/10. Mollies score 8/10, but the shared pH is a single point at pH 7.5–7.5, and Seriously Fish says mollies become disease-prone in water that is not hard and alkaline. Endler’s livebearers score 8/10 and share only 15–15 dGH of hardness. Of the four, the guppy is the easiest match; the guppy tank mates guide covers its other companions.

Other bottom dwellers

Kuhli loaches score 9/10. Seriously Fish describes them as peaceful with their own kind and other fish, and they are nocturnal, so they use the floor at different hours; the page on fish that live with kuhli loaches ranks their other companions. The bristlenose pleco scores 9/10, but Aquarium Co-Op notes that males can guard against other bottom dwellers, so give it a cave of its own. The bristlenose pleco tank mates page explains that territorial streak.

Semi-aggressive centrepiece fish

Dwarf gouramis score 9/10 and bettas 7/10 with corys, because neither competes for the bottom. Both are semi-aggressive, which raises the shared tank to 40 US gal (151 L). The page on fish that live with bettas ranks corys among the stronger betta companions. Angelfish score 7/10 but need 90 US gal (341 L) together; the cory is large enough that the angelfish’s appetite for neon-sized fish does not apply, and the compatible tank mates for angelfish page explains where that line falls.

Which fish should never live with corydoras?

Oscars, goldfish and discus fail outright with corydoras in our data, each for a different reason.

Oscar

Oscars score 3/10. Seriously Fish and Aquarium Co-Op both describe a predator that eats any fish small enough to swallow, and at 14 in (35.6 cm) an adult oscar is several times longer than a 3 in (7.6 cm) cory. Water overlap does not rescue the pairing: the two share 74–80 °F (23–27 °C), but the size gap is enough on its own.

Goldfish

Goldfish score 3/10. The two share almost no temperature range, only 70–70 °F (21–21 °C), because goldfish are coldwater fish kept at 59–70 °F (15–21 °C). Aquarium Co-Op adds a physical hazard in its goldfish tank mates guide: corys are among the fish goldfish eat, and spiny catfish such as corydoras can lodge in a goldfish’s gills if swallowed.

Discus

Discus score 3/10. They are peaceful and would not harm a cory, but they need 79–86 °F (26–30 °C), so the pair shares only 79–81 °F (26–27 °C). Keeping a tank at the very top of the cory’s range leaves no margin for heater error. Readers planning a discus tank should start from the discus tank mates ranking instead.

Can corydoras live with shrimp and snails?

Corydoras live well with snails, and probably with adult shrimp, but no source in our data says directly whether corys eat dwarf shrimp.

Snails

Mystery snails score 9/10, and Aquarium Co-Op lists corydoras by name among the fish mystery snails can live with. Nerite snails score 8/10; Shrimp and Snail Breeder calls them peaceful herbivores that compete only with other snails for food. Both snails want harder, more alkaline water than corys, so the shared pH narrows to pH 7.2–7.5.

Shrimp

Cherry shrimp score 7/10 and amano shrimp 7/10 with corys. Water is not the problem: the cherry shrimp’s range sits almost entirely inside the cory’s. The lower score comes from a gap in the evidence. Our corydoras data records that corys eat eggs, including their own, but none of the cited sources states whether they eat dwarf shrimp, so the method caps the size factor rather than assuming safety. Aquarium Co-Op says almost all fish eat baby shrimp, which is the risk to plan for. The cherry shrimp compatibility guide explains how each fish is scored against shrimp.

Which corydoras tank mates fit a 10, 20 or 29-gallon tank?

Corydoras need at least 20 US gal (76 L) themselves, so a 20-gallon tank is the starting point and a 10-gallon tank is too small for the bronze cory. Aquarium Co-Op recommends 20 gallons or more for most non-dwarf corys, and Seriously Fish’s 80 × 30 cm base works out at about the same volume.

10-gallon tank

A 10-gallon tank falls below the bronze cory’s minimum, so we do not list it as a cory tank. Co-Op’s wording leaves room for dwarf corydoras species, but our data does not cover them. For small tanks, see the guide to choosing fish for a 10-gallon community tank.

20-gallon tank

At 20 gallons most peaceful pairings fit: neon tetras, harlequin rasboras, cardinal tetras, kuhli loaches, guppies and both snails all calculate at 20 US gal (76 L) with corys. That figure covers one pairing at a time. A group of six corys plus a school of 8 tetras is a larger load, so check the full plan in the stocking calculator.

40 gallons and larger

The semi-aggressive centrepiece fish need more room. Dwarf gouramis and bettas calculate at 40 US gal (151 L) with corys, because the method adds a margin for semi-aggressive species, and angelfish at 90 US gal (341 L).

Are corydoras a clean-up crew for other fish?

No. Corydoras are often sold as tank cleaners, but Aquarium Co-Op notes that they are not primarily algae eaters, and Seriously Fish describes a foraging omnivore that needs its own sinking dried foods plus small live or frozen foods such as bloodworm. A cory that lives only on what falls past fast mid-water tank mates may go hungry, which is the real cost of pairing them with greedy feeders.

A second misconception is that one or two corys are enough. PlanetCatfish and Aquarium Co-Op both say to keep at least 6 of the same species. Sources differ on the minimum: Seriously Fish gives four to six and Practical Fishkeeping at least three, with more being better. Mixing several species of one each does not satisfy the shoaling need.

What goes wrong in a corydoras community tank?

Most corydoras problems come from the tank rather than the tank mates. Three failure points recur across the sources, listed from most to least common.

• Rough substrate. PlanetCatfish and Seriously Fish warn that rough or chipped gravel can damage the barbels while corys dig, and recommend sand or smooth rounded gravel.
• A tank mate that grows into a predator. Aquarium Co-Op says corys are eaten by any tank mate large enough to attack them. A juvenile oscar or goldfish may look harmless next to a cory but outgrows it.
• Lost eggs. Corys spawn readily, but Aquarium Co-Op says all fish, parents included, eat cory eggs. In a community tank, expect few fry unless the eggs are moved.

Temperature drift is the quieter risk. The cory’s upper limit of 70–81 °F (21–27 °C) sits below the preferred range of warm-water fish, so a pairing such as corys with discus fails gradually rather than at once.