Candidate
Congo tetra
Phenacogrammus interruptus
Open full care profile →Photo identification · reviewed 2026-07-31
Congo tetra vs black skirt tetra
Adult scale, iridescence and flowing male fins separate the Congo tetra from the smaller black skirt tetra.
Candidate
Black skirt tetra
Gymnocorymbus ternetzi
Open full care profile →Interactive observation guide
Inspect one clue at a time
Use the photographs above, then select each clue. Do not make an identification from one feature alone.
Adult Congo tetras are longer and develop a rainbow sheen; males have extended central tail rays and ornate fins.
Care reality check
Compare the adult requirements
A visual identification changes which limits you should plan around.
| Requirement | Congo tetra | Black skirt tetra |
|---|---|---|
| Adult size | 6–9 cm | 5–6 cm |
| Minimum tank | 150 L · 100 cm | 75 L · 75 cm |
| Temperature | 23–28°C | 20–27°C |
| pH | 6–7.5 | 6–8 |
| GH | 3–18 dGH | 4–18 dGH |
| Social minimum | 8 | 8 |
| Temperament | peaceful and active | boisterous |
Visible differences
Clues to inspect
- Adult Congo tetras are longer and develop a rainbow sheen; males have extended central tail rays and ornate fins.
- Black skirt tetras are shorter and much deeper-bodied, with vertical shoulder bars and a skirt-like anal fin.
- Young Congo tetras can be plain silver, so shop-size comparisons underestimate the adult difference.
Shared traits
Why they are confused
- Both are social midwater tetras with a relatively deep body.
- Both should be assessed as groups, not as one decorative specimen.
Why it matters
Do not stop at the name
Congo tetras need substantially more tank length and a calmer community that protects their fins.
Uncertainty
When a photo is not enough
Juvenile sex and poor shop condition suppress the Congo tetra's defining adult ornamentation.