Fish comparison
Cardinal Tetra vs German Blue Ram
How the Cardinal Tetra and German Blue Ram compare on care, size, water and temperament, and which fish suits your tank.
By Mike ElmiraUpdated
TL;DR, Cardinal Tetra vs German Blue Ram
The Cardinal Tetra and the German Blue Ram 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 26 to 27 °C and pH 5 to 6.5, so a single tank can suit either one. The Cardinal Tetra is the more forgiving of the two, which matters if this is an early tank, while the German Blue Ram rewards a bit more attention. For a calm community the gentler Cardinal Tetra slots in more easily.
Group compatibility overview
Excellent fit
Every key parameter overlaps and no major conflicts surfaced.
3 notes
Temperature
- Cardinal Tetra23–27 °C
- German Blue Ram26–29 °C
pH
- Cardinal Tetra4.5–6.5
- German Blue Ram5–7
Hardness
- Cardinal Tetra1–6 dGH
- German Blue Ram1–8 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.
- Demanding species presentGerman Blue Ram are difficulty 4+. Stable parameters and weekly maintenance are non-negotiable.
- 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 |  FishGerman Blue RamMikrogeophagus ramirezi |
|---|---|---|
| Category | Fish | Fish |
| Origin | Upper Orinoco and Rio Negro basins | Orinoco basin, Venezuela & Colombia |
| Family | Characidae | Cichlidae |
| Temperature | 23–27 °C | 26–29 °C |
| pH | 4.5–6.5 | 5.0–7.0 |
| Hardness (dGH) | 1–6 | 1–8 |
| Flow rate | Low | Low |
| Min tank | 75 L | 75 L (pair) |
| Adult size | 4–5 cm | 5–7 cm |
| Difficulty | 3 / 5 | 4 / 5 |
| Lifespan | 4–6 yrs | 2–3 yrs |
| Diet | Omnivore | Omnivore |
| Water column | Mid | Mid to Bottom |
| Schooling | Yes | Pair |
| Plant safe | Yes | Yes |
| Shrimp safe | Mostly (may eat shrimplets) | Risky with dwarf shrimp |
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 German Blue Ram together?
Yes. Their temperature and pH ranges overlap around 26 to 27 °C and pH 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 German Blue Ram?
The Cardinal Tetra is the easier of the two, closer to middle-of-the-road, while the German Blue Ram leans demanding.
Do Cardinal Tetra and German Blue Ram need the same water?
Close to it. Aim for 26 to 27 °C and pH 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 German Blue Ram?
Temperament is the big one. The Cardinal Tetra is peaceful and the German Blue Ram is territorial when breeding, which changes who you can house them with.