Species profile
Costello Tetra
Hemigrammus hyanuary
Peaceful
Easy care
80 L minimum aquarium
3.5–4.5 cm adult size
Midwater
Minimum group: 10
About this species
General notes for hobby use.
Small peaceful shoaling tetra; group of ten or more recommended.
Water parameters
Suggested general range for long-term care.
Temperature
23–27 °C
pH
6–7.2
GH
2–12 dGH
KH
Not yet documented
Flow preference
Low–moderate
Data confidence
Verified
Behaviour
General behaviour traits used by TanksConnected compatibility checks.
Minimum group size
Minimum group: 10
Tank zone
Midwater
Territory level
None
Predation risk
Tiny fry
Bioload factor
0.5
Peaceful community shoaler that shows best behaviour and colour in a substantial group.
Compatibility flags
Quick cautions for common tank-planning issues.
Fin nipper
No
Plant safe
Yes
Shrimp safe
Yes
Snail safe
Yes
Cave breeder
No
Digs substrate
No
Jump risk
Low
Natural history & care
Research-backed context for long-term aquarium care.
Lifespan
Not yet documented
Diet type
Omnivore
Minimum aquarium volume
80 L
Minimum footprint
80 × 30 cm
Accepted scientific name
Hemigrammus hyanuary
Alternative names
January Tetra, Green Neon Tetra (historic/confusing trade use)
Native range
Brazil and Peru, Amazon basin.
Natural habitat
Soft, acidic forest waters. Use a mature planted/botanical aquarium with shaded margins and open central swimming room.
Diet & feeding
Small quality dry foods with regular frozen/live micro-invertebrates.
Breeding & sexing
Research-backed guidance for identifying sexes and reproductive behaviour.
Sexing
Females are larger/fuller; males may possess a small anal-fin hook.
Breeding
Egg-scattering characin; breeding requires soft acidic water and protection of eggs from adults/light.