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Blackline penguinfish
A black side stripe turns down into the lower tail lobe
The stripe reaches forward to near the gill cover and continues into the lower tail lobe. Trade names such as penguin tetra can refer to more than one species.
- Adult length
- Up to 3.6 cm (standard length, without the tail fin)
- Water temperature
- 22–28 °C
- pH
- 5.5–8
- Hardness
- 5–19 dGH
- Native range
- Native to the upper Amazon basin in Peru and the Araguaia River in Brazil.
- Natural habitat
- Unknown
Provide a group and swimming space. Small groups may chase or nip.
Appearance and identification
In the similar Thayeria obliqua, the dark stripe fades before reaching the front of the dorsal-fin region.
Same-species behaviour
Keep at least six, preferably ten or more.
Space requirements
Allow a 60 × 38 cm footprint for a small group, larger for larger groups. Keep a continuous swimming lane.
Diet and feeding
Offer small live or frozen foods alongside suitable prepared foods, checking that less assertive individuals eat.
Compatibility limits
Avoid much larger or excessively active companions. It feeds on small invertebrates, so ornamental shrimp are at risk.
Aquarium environment
Plants and floating leaves can provide shade without filling the swimming lane.
Similar and related fish
Sources
www.fishbase.se ↗ 2026-10-25
www.seriouslyfish.com ↗ 2026-10-21
www.mw-fish.com.tw ↗ 2026-10-21
www.greenflow.hk ↗ 2026-10-21
researcharchive.calacademy.org ↗ 2026-10-22