Fish comparison
Cardinal Tetra vs Scarlet Badis
How the Cardinal Tetra and Scarlet Badis compare on care, size, water and temperament, and which fish suits your tank.
By Mike ElmiraUpdated
TL;DR, Cardinal Tetra vs Scarlet Badis
The Cardinal Tetra and the Scarlet Badis come up together a lot when people are choosing a fish, and they are close enough to weigh side by side. Both are happy somewhere around 23 to 26 °C and pH 6.5 to 6.5, so a single tank can suit either one. Neither is harder than the other to keep, so the choice comes down to look and stocking rather than skill. If tank space is tight, the Scarlet Badis needs less room to feel settled; give the Cardinal Tetra the nod when you have the litres to spare.
Group compatibility overview
Good fit
Workable as-is, only minor advisories to plan around.
1 warning · 2 notes
Temperature
- Cardinal Tetra23–27 °C
- Scarlet Badis20–26 °C
pH
- Cardinal Tetra4.5–6.5
- Scarlet Badis6.5–7.5
Hardness
- Cardinal Tetra1–6 dGH
- Scarlet Badis5–15 dGH
What to plan for
- Narrow pH overlapTarget pH is 6.5–6.5. Test weekly; use buffered substrate or remineraliser to keep it stable.
- Cardinal Tetra schools, stock at least 8You've planned for 1 cardinal tetra. Cardinal Tetra need a group of at least 8 to feel safe and shoal naturally, below that they're stressed and lose colour. Dial up the count, or remove the species.
- 67% of your fish swim in the midHeavy concentration in a single zone. Spreading stocking across all three levels makes the tank read fuller for the same bioload.
Full attributes
Every parameter, side by side| Parameter |  FishCardinal TetraParacheirodon axelrodi |  FishScarlet BadisDario dario |
|---|---|---|
| Category | Fish | Fish |
| Origin | Upper Orinoco and Rio Negro basins | West Bengal and Assam, India |
| Family | Characidae | Badidae |
| Temperature | 23–27 °C | 20–26 °C |
| pH | 4.5–6.5 | 6.5–7.5 |
| Hardness (dGH) | 1–6 | 5–15 |
| Flow rate | Low | Still to Low |
| Min tank | 75 L | 30 L |
| Adult size | 4–5 cm | 1.5–2 cm |
| Difficulty | 3 / 5 | 3 / 5 |
| Lifespan | 4–6 yrs | 3–4 yrs |
| Diet | Omnivore | Micropredator |
| Water column | Mid | Mid to Bottom |
| Schooling | Yes | Harem (1 male, 3+ females) |
| Plant safe | Yes | Yes |
| Shrimp safe | Mostly (may eat shrimplets) | No (eats shrimplets; risky with adult Neocaridina too) |
Frequently asked questions
Direct answers to the questions search engines and AI assistants surface most often about this species.
Can you keep Cardinal Tetra and Scarlet Badis together?
Yes. Their temperature and pH ranges overlap around 23 to 26 °C and pH 6.5 to 6.5, so one set of water conditions keeps both comfortable. Match group sizes and cover the usual planted-tank basics and they share a tank fine.
Which is easier to keep, the Cardinal Tetra or the Scarlet Badis?
They sit at the same care level, both middle-of-the-road, so neither is the obvious beginner pick. The decision is really about the look you're after.
Do Cardinal Tetra and Scarlet Badis need the same water?
Close to it. Aim for 23 to 26 °C and pH 6.5 to 6.5 and you're in the shared sweet spot for both. Full ranges are in the table above.
What's the main difference between the Cardinal Tetra and the Scarlet Badis?
Space. The Cardinal Tetra wants about 75 litres minimum and the Scarlet Badis around 30, so tank size can settle it.