Fish comparison
Cardinal Tetra vs Dwarf Pencilfish
How the Cardinal Tetra and Dwarf Pencilfish compare on care, size, water and temperament, and which fish suits your tank.
By Mike ElmiraUpdated
TL;DR, Cardinal Tetra vs Dwarf Pencilfish
The Cardinal Tetra and the Dwarf Pencilfish 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 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 Dwarf Pencilfish needs less room to feel settled; give the Cardinal 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
- Dwarf Pencilfish22–28 °C
pH
- Cardinal Tetra4.5–6.5
- Dwarf Pencilfish5–7
Hardness
- Cardinal Tetra1–6 dGH
- Dwarf Pencilfish1–8 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.
- Dwarf Pencilfish schools, stock at least 6You've planned for 1 dwarf pencilfish. Dwarf Pencilfish 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.
- 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 |  FishDwarf PencilfishNannostomus marginatus |
|---|---|---|
| Category | Fish | Fish |
| Origin | Upper Orinoco and Rio Negro basins | Western Guyana, Suriname, lower Amazon basin |
| Family | Characidae | Lebiasinidae |
| Temperature | 23–27 °C | 22–28 °C |
| pH | 4.5–6.5 | 5.0–7.0 |
| Hardness (dGH) | 1–6 | 1–8 |
| Flow rate | Low | Still to Low |
| Min tank | 75 L | 60 L |
| Adult size | 4–5 cm | 3–3.5 cm |
| Difficulty | 3 / 5 | 3 / 5 |
| Lifespan | 4–6 yrs | 3–5 yrs |
| Diet | Omnivore | Micropredator |
| Water column | Mid | Mid to Top |
| Schooling | Yes | Yes (loose shoal) |
| Plant safe | Yes | Yes |
| Shrimp safe | Mostly (may eat shrimplets) | Yes (adult 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 Dwarf Pencilfish together?
Yes. Their temperature and pH ranges overlap around 23 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 Dwarf Pencilfish?
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 Dwarf Pencilfish need the same water?
Close to it. Aim for 23 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 Dwarf Pencilfish?
Space. The Cardinal Tetra wants about 75 litres minimum and the Dwarf Pencilfish around 60, so tank size can settle it.