Fish comparison
Cardinal Tetra vs Congo Tetra
How the Cardinal Tetra and Congo Tetra compare on care, size, water and temperament, and which fish suits your tank.
By Mike ElmiraUpdated
TL;DR, Cardinal Tetra vs Congo Tetra
The Cardinal Tetra and the Congo Tetra 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 27 °C and pH 6 to 6.5, so a single tank can suit either one. The Congo Tetra is the more forgiving of the two, which matters if this is an early tank, while the Cardinal Tetra rewards a bit more attention. If tank space is tight, the Cardinal Tetra needs less room to feel settled; give the Congo Tetra the nod when you have the litres to spare.
Group compatibility overview
Excellent fit
Every key parameter overlaps and no major conflicts surfaced.
4 notes
Temperature
- Cardinal Tetra23–27 °C
- Congo Tetra23–28 °C
pH
- Cardinal Tetra4.5–6.5
- Congo Tetra6–7.5
Hardness
- Cardinal Tetra1–6 dGH
- Congo Tetra3–15 dGH
What to plan for
- 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.
- Congo Tetra schools, stock at least 6You've planned for 1 congo tetra. Congo Tetra need a group of at least 6 to feel safe and shoal naturally, below that they're stressed and lose colour. Dial up the count, or remove the species.
- No bottom teamNo bottom-dwelling fish or shrimp. A small group of corydoras or a shrimp colony picks up leftover food and keeps detritus in check.
- 100% 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 |  FishCongo TetraPhenacogrammus interruptus |
|---|---|---|
| Category | Fish | Fish |
| Origin | Upper Orinoco and Rio Negro basins | Congo River basin, Democratic Republic of Congo |
| Family | Characidae | Alestidae |
| Temperature | 23–27 °C | 23–28 °C |
| pH | 4.5–6.5 | 6.0–7.5 |
| Hardness (dGH) | 1–6 | 3–15 |
| Flow rate | Low | Low to Medium |
| Min tank | 75 L | 150 L |
| Adult size | 4–5 cm | 7–9 cm |
| Difficulty | 3 / 5 | 2 / 5 |
| Lifespan | 4–6 yrs | 3–5 yrs |
| Diet | Omnivore | Omnivore |
| Water column | Mid | Mid |
| Schooling | Yes | Yes |
| Plant safe | Yes | Mostly (may nibble very soft new growth) |
| Shrimp safe | Mostly (may eat shrimplets) | No |
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 Congo Tetra together?
Yes. Their temperature and pH ranges overlap around 23 to 27 °C and pH 6 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 Congo Tetra?
The Congo Tetra is the easier of the two, closer to beginner-friendly, while the Cardinal Tetra leans middle-of-the-road.
Do Cardinal Tetra and Congo Tetra need the same water?
Close to it. Aim for 23 to 27 °C and pH 6 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 Congo Tetra?
Space. The Cardinal Tetra wants about 75 litres minimum and the Congo Tetra around 150, so tank size can settle it.