Fish comparison
Cardinal Tetra vs Otocinclus (Common)
How the Cardinal Tetra and Otocinclus (Common) compare on care, size, water and temperament, and which fish suits your tank.
By Mike ElmiraUpdated
TL;DR, Cardinal Tetra vs Otocinclus (Common)
The Cardinal Tetra and the Otocinclus (Common) 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 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 Otocinclus (Common) 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.
2 notes
Temperature
- Cardinal Tetra23–27 °C
- Otocinclus (Common)20–26 °C
pH
- Cardinal Tetra4.5–6.5
- Otocinclus (Common)6–7.5
Hardness
- Cardinal Tetra1–6 dGH
- Otocinclus (Common)2–10 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.
- Otocinclus (Common) schools, stock at least 6You've planned for 1 otocinclus (common). Otocinclus (Common) 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.
Full attributes
Every parameter, side by side| Parameter |  FishCardinal TetraParacheirodon axelrodi |  FishOtocinclus (Common)Otocinclus vittatus |
|---|---|---|
| Category | Fish | Fish |
| Origin | Upper Orinoco and Rio Negro basins | Northern and central South America |
| Family | Characidae | Loricariidae |
| Temperature | 23–27 °C | 20–26 °C |
| pH | 4.5–6.5 | 6.0–7.5 |
| Hardness (dGH) | 1–6 | 2–10 |
| Flow rate | Low | Medium to High |
| Min tank | 75 L | 60 L |
| Adult size | 4–5 cm | 3.5–5 cm |
| Difficulty | 3 / 5 | 3 / 5 |
| Lifespan | 4–6 yrs | 3–5 yrs |
| Diet | Omnivore | Herbivore (algae) |
| Water column | Mid | Bottom (grazes everywhere) |
| Schooling | Yes | Yes |
| Plant safe | Yes | Yes |
| Shrimp safe | Mostly (may eat shrimplets) | Yes |
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 Otocinclus (Common) together?
Yes. Their temperature and pH ranges overlap around 23 to 26 °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 Otocinclus (Common)?
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 Otocinclus (Common) need the same water?
Close to it. Aim for 23 to 26 °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 Otocinclus (Common)?
Space. The Cardinal Tetra wants about 75 litres minimum and the Otocinclus (Common) around 60, so tank size can settle it.