Corydoras vs kuhli loach: which should you choose?
AquaLog guide · Published
In short: Both are peaceful, beginner-rated bottom-dwellers that need at least 75 L (20 US gal) and soft substrate. Choose corydoras for a group of six or more you will see sifting the sand, and kuhli loaches for softer, more acidic water and a fish that mostly appears after lights out. They live together well at 23–27 °C (73–81 °F) and pH 6–7.5.
How do they compare?
| Bronze corydoras | Kuhli loach | |
|---|---|---|
| Minimum tank | 75 L (20 US gal) | 75 L (20 US gal) |
| Temperature | 22–27 °C (72–81 °F) | 23–29 °C (73–84 °F) |
| pH | 6–7.8 | 5.5–7.5 |
| Hardness | 2–18 dGH | 2–12 dGH |
| Adult size | 6.5 cm (2.6 in) | 9 cm (3.5 in) |
| Temperament | Peaceful | Peaceful |
| Group size | 6 or more | 5 or more |
| Care level | Beginner | Beginner |
| Lifespan | 5–10 years | 5–10 years |
| Diet | Omnivore: sinking pellets, frozen bloodworm, scraps from above | Omnivore: sinking pellets, frozen bloodworm, wafers |
| Behaviour | Sociable, armoured; constantly sifts sand for food | Eel-shaped; hides by day and forages in groups after lights out |
All figures come from our care guide: see bronze corydoras and kuhli loach. We compare the bronze corydoras here. Other corydoras, such as the panda and pygmy, have their own numbers.
What is the real difference?
When you see them. Bronze corydoras are sociable armoured catfish that spend their time sifting the sand for food. Kuhli loaches are banded and eel-shaped; they hide all day and come out to forage in groups after lights out. Water is the second difference. Our care guide lists kuhlis for softer, more acidic water: pH 5.5–7.5 and up to 12 dGH. Bronze corydoras take up to pH 7.8 and 18 dGH.
Choose corydoras if…
- You want a bottom-dweller you will see often, busy at the sand in a group.
- Your water is harder or more alkaline. Bronze corydoras are listed up to pH 7.8 and 18 dGH.
- You'd like to try breeding. Our data says a cool water change can trigger spawning, and rates breeding intermediate, against advanced for kuhlis.
- Your mid-water fish are on its list: neon tetras, harlequin rasboras, honey gouramis and angelfish.
Choose kuhli loaches if…
- Your water is soft and acidic, down to pH 5.5.
- You keep a betta or gouramis. Our kuhli data lists both as good tank mates.
- You can give them hiding places and enjoy a fish you mostly see around lights out.
Can corydoras and kuhli loaches live together?
Yes. Our kuhli loach data lists corydoras as a good tank mate, and their ranges overlap at 23–27 °C (73–81 °F), pH 6–7.5 and 2–12 dGH. Both are peaceful, both avoid large cichlids, and the kuhlis do most of their foraging after dark.
Our care guide gives each species a minimum of 75 L (20 US gal), so a shared tank should be at least that. Start there, add the fish a few at a time, and let your water tests tell you whether the tank can take more: ammonia and nitrite should stay at 0 ppm and nitrate below about 20–40 ppm. The aquarium stocking checker runs the same range, group-size and avoid-list checks for the rest of your stock. Make sure sinking food still reaches the bottom after lights out, when the kuhlis feed.
What should a buyer know?
- Substrate matters for both. Our data lists sharp gravel (it wrecks corydoras barbels) and coarse gravel (it shreds kuhli skin) among things to avoid. Kuhlis also dig and bury themselves, so soft sand suits both.
- The name covers more than one species. Our care guide lists the kuhli loach as Pangio kuhlii. Seriously Fish notes that true P. kuhlii is currently considered endemic to Java and has possibly never been in the aquarium trade, and that the fish sold as kuhli loaches are more likely P. semicincta or a close relative. Its ranges for P. semicincta are cooler, softer and more acidic than ours: 21–26 °C (70–79 °F) against our 23–29 °C, for example. If your tank sits near the warm or hard end of the ranges above, read its page (listed under sources) as well.
- Cover the filter intake. Our kuhli data lists escaping through filter intakes as a common problem. Fit a guard or sponge over the intake, and keep a lid on, as loaches can jump.
- Watch for white spots. Our data notes kuhlis show ich spots early. If they appear, test the water, do a partial water change and ask an experienced aquarist or a vet before using any treatment; then follow the product label.
- Both live a long time: 5–10 years.
For more options, see bottom-dwelling aquarium fish, and plan the rest of the tank with how to choose compatible tank mates. In AquaLog, the "Will it fit your tank?" check compares either species with your logged tank's size, water type, temperature and pH.