Least Killifish
Heterandria formosa
Family: Poeciliidae • Origin: Various
Least Killifish (Heterandria formosa) is a peaceful livebearer reaching 1.2 inches. Keep in groups of 4+. Minimum tank size: 5 gallons.
Min Tank
5 gal
Max Size
1.2"
Temperature
68-78°F
pH
7-8
Lifespan
2 years
School Size
4+
Swim Level
middle
Hardness
5-15 dGH
peacefulintermediateomnivoreschooling
Care Tips
- • Max size: 1.2 inches
- • Temperature: 68-78°F
- • pH: 7-8
- • Schooling — keep 4+ together
- • peaceful temperament — safe with community fish
Feeding: Standard omnivore diet. Accepts foods appropriate for Poeciliidae species.
Compatibility Notes: Typical peaceful Poeciliidae species.
Tank Setup & Water Parameters
Tank Requirements
- Minimum Tank Size
- 5 gallons
- Recommended Tank Size
- 8 gallons
- Swimming Level
- middle
- Minimum School Size
- 4+ fish
Water Parameters
- Temperature
- 68–78°F
- pH Range
- 7–8
- Hardness (dGH)
- 5–15
- Water Type
- freshwater
Behavior & Temperament
- Temperament
- peaceful
- Aggression Level
- 1/5
- Schooling
- Yes
- Territorial
- No
- Fin Nipper
- No
- Predatory
- No
- Diet Type
- omnivore
- Growth Rate
- moderate
Typical peaceful Poeciliidae species.
Breeding
- Breeding Type
- live bearer
- Breeding Difficulty
- moderate
- Lifespan
- 2 years
Ideal For
5 gallon
Compatible Tank Mates
View all →
Black Neon Tetra
Hyphessobrycon herbertaxelrodi
73-81°FpH 5.5-7.510+ gal
peacefulschooling 6+1.6"
Serpae Tetra
Hyphessobrycon eques
72-82°FpH 6-7.520+ gal
semi-aggressiveschooling 6+1.75"
Black Skirt Tetra
Gymnocorymbus ternetzi
70-82°FpH 6-7.515+ gal
peacefulschooling 5+3"
Congo Tetra
Phenacogrammus interruptus
75-81°FpH 6-7.530+ gal
peacefulschooling 6+3.5"
Guppy
Poecilia reticulata
72-82°FpH 6.8-7.810+ gal
peacefulschooling 3+2.5"
Endler's Livebearer
Poecilia wingei
72-82°FpH 6.5-85+ gal
peacefulschooling 3+1.5"
Similar Species
Scarlet Livebearer
Micropoecilia picta
75-82°FpH 7-85+ gal
peacefulschooling 4+1.2"
Norman's Lampeye
Poropanchax normani
72-82°FpH 6.5-7.55+ gal
peacefulschooling 8+1.5"
Guppy
Poecilia reticulata
72-82°FpH 6.8-7.810+ gal
peacefulschooling 3+2.5"
Endler's Livebearer
Poecilia wingei
72-82°FpH 6.5-85+ gal
peacefulschooling 3+1.5"