Species profile
Ruby Tetra
Axelrodia riesei
Peaceful
Moderate care
35 L minimum aquarium
2–4 cm adult size
Midwater
Minimum group: 10
About this species
General notes for hobby use.
Tiny soft-water tetra from northern South America. Best in a mature, shaded aquarium with a large shoal and tiny peaceful companions.
Water parameters
Suggested general range for long-term care.
Temperature
20–26 °C
pH
4.5–7
GH
0–8 dGH
KH
Not yet documented
Flow preference
Low
Data confidence
Verified
Behaviour
General behaviour traits used by TanksConnected compatibility checks.
Minimum group size
Minimum group: 10
Tank zone
Midwater
Territory level
Low
Predation risk
Shrimp fry
Bioload factor
0.4
Very peaceful and easily intimidated or outcompeted. Keep a good-sized shoal with similarly tiny calm species.
Compatibility flags
Quick cautions for common tank-planning issues.
Fin nipper
No
Plant safe
Yes
Shrimp safe
No / caution
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
Carnivore
Minimum aquarium volume
35 L
Minimum footprint
45 × 30 cm
Accepted scientific name
Axelrodia riesei
Alternative names
Ruby Tetra
Native range
Upper Orinoco/Meta region of Colombia and Venezuela; reports from the upper Rio Negro require confirmation.
Natural habitat
Small, sluggish forest tributaries with vegetation, leaf litter and often tannin-stained soft acidic water. Gentle filtration and subdued light are appropriate.
Diet & feeding
Micropredator. Feed very small live/frozen foods and suitably tiny high-quality prepared foods.
Breeding & sexing
Research-backed guidance for identifying sexes and reproductive behaviour.
Sexing
Males are generally slimmer and more intensely coloured; females become fuller-bodied when mature.
Breeding
Egg-scattering non-guarder among fine vegetation; very soft acidic water is typically used for deliberate breeding.