Neon tetra vs cardinal tetra: which should you choose?
AquaLog guide · Published
In short: Choose the neon tetra if you want the easier fish: it is rated beginner, needs 60 L (16 US gal) and takes cooler, slightly harder water. Choose the cardinal tetra if your water is soft and warm, 24–29 °C (75–84 °F), and you can give it at least 75 L (20 US gal). They can share a tank kept at 24–27 °C (75–81 °F) and pH 5.5–7, with eight or more of each.
How do they compare?
| Neon tetra | Cardinal tetra | |
|---|---|---|
| Minimum tank | 60 L (16 US gal) | 75 L (20 US gal) |
| Temperature | 21–27 °C (70–81 °F) | 24–29 °C (75–84 °F) |
| pH | 5.5–7.5 | 4.5–7 |
| Hardness | 1–12 dGH | 1–8 dGH |
| Adult size | 3.5 cm (1.4 in) | 4.5 cm (1.8 in) |
| Temperament | Peaceful | Peaceful |
| Group size | 8 or more | 8 or more |
| Care level | Beginner | Intermediate |
| Lifespan | 3–8 years | 4–8 years |
| Diet | Omnivore: micro pellets, crushed flake, frozen daphnia and baby brine | Omnivore: small frozen foods, micro pellets, quality flake |
| Where it swims | Mid-water | Mid-water |
All figures come from our care guide. The full pages are neon tetra and cardinal tetra.
How do you tell them apart?
Both have a bright blue line with red below it. On a cardinal, the red runs the full length of the body. A neon has noticeably less red, and its blue line is narrower and stops further from the tail. Cardinals also grow about a centimetre longer: 4.5 cm (1.8 in) against 3.5 cm (1.4 in).
Choose the neon tetra if…
- You are new to fishkeeping. Our care guide rates the neon beginner and the cardinal intermediate.
- Your tank is under 75 litres (20 US gal). The neon's minimum is 60 L (16 US gal); the cardinal's is 75 L (20 US gal).
- Your tap water is near neutral or moderately hard. Neons are listed up to pH 7.5 and 12 dGH; cardinals only to pH 7 and 8 dGH.
- Your room runs cool. The neon's range starts at 21 °C (70 °F), the cardinal's at 24 °C (75 °F).
Choose the cardinal tetra if…
- Your water is soft and acidic. Cardinals are listed down to pH 4.5 and up to only 8 dGH.
- Your tank runs warm. The cardinal's range reaches 29 °C (84 °F), two degrees above the neon's limit, which gives more margin in a hot summer.
- You want the bigger, redder fish and can give it at least 75 L (20 US gal).
- You keep discus. Our data lists discus as a good tank mate for cardinals, not neons. Discus need 28–31 °C (82–88 °F). That is above the neon's range entirely, and shares only 28–29 °C (82–84 °F) with the cardinal, the top of its range.
Can neon and cardinal tetras live together?
Yes. Their ranges overlap at 24–27 °C (75–81 °F), pH 5.5–7 and 1–8 dGH. Both are peaceful mid-water fish, and neither appears on the other's list of fish to avoid. Both list corydoras such as the bronze corydoras and otocinclus as good tank mates. Plan on at least the larger minimum, 75 L (20 US gal), and keep a full group of eight or more of each species, not eight fish in total. The aquarium stocking checker runs the same range, group-size and avoid-list checks for any mix of species.
Their avoid lists differ, so follow both. Neons list angelfish, oscars and large cichlids. Cardinals list tiger barbs and large cichlids.
What else should a buyer know?
- Where they come from. Most neons sold are commercially bred. Cardinals are now bred commercially on a large scale too, but a significant share are still wild-caught in their native Rio Negro and Orinoco basins, or come from community-led projects such as Project Piaba on the middle Rio Negro.
- Wild fish need stable water. Wild-caught cardinals cope less well with worsening water than farmed fish, and our cardinal data lists bacterial infections after shipping. Add them only to a fully cycled, stable tank. See how to cycle an aquarium.
- Choose neons with care. Long commercial breeding has weakened many farmed neons, and our neon data lists poor stock quality and neon tetra disease among its common problems. Neon tetra disease is a microsporidian infection that is very hard to treat once advanced. In the shop, pass over any tank where fish are restless, show white patches or hang apart from the group. If fish at home show these signs, isolate them and ask a vet or an experienced aquarist.
- Breeding. Both are rated advanced to breed, and cardinals are rarely bred at home.
Not sure your water suits either fish? Test pH and hardness first: aquarium water parameters explained shows how. For more options, see fish for soft, acidic water and best freshwater fish for beginners. Signed in to AquaLog, the "Will it fit your tank?" check compares either fish with your logged tank's size, water type, temperature and pH.