Least killifish
Heterandria formosa
- Tank length
- 10 cm4 in
- Start with
- 5
- Temperature
- 20–26 °C68–79 °F
- pH
- 7–8
- Adult size
- 2.5 cm1 in
- Lifespan
- 1–3 yrs
Among the smallest vertebrates; keep in a species or nano tank because almost any community fish will eat it.Among the smallest vertebrates; keep in a species or nano tank because almost any community fish will eat it.
Tank sizes
Good tankmates
Avoid with
- African clawed frog
African clawed frog may eat Least killifishAfrican clawed frog may eat Least killifish
- Brilliant rasbora
No shared pH rangeNo shared pH range
- Irian Jaya rainbowfish
No shared temperature rangeNo shared temperature range
Lambchop rasboraNo shared pH rangeNo shared pH range
- Abei puffer
Abei puffer may eat Least killifishAbei puffer may eat Least killifish
- African butterflyfish
African butterflyfish may eat Least killifishAfrican butterflyfish may eat Least killifish
- African knifefish
African knifefish may eat Least killifishAfrican knifefish may eat Least killifish
- African pike
African pike may eat Least killifishAfrican pike may eat Least killifish
- Alligator gar
Alligator gar may eat Least killifishAlligator gar may eat Least killifish
- Altum angelfish
No shared pH rangeNo shared pH range
- Amazon leaffish
No shared pH rangeNo shared pH range
- Amazon toadfish
Amazon toadfish may eat Least killifishAmazon toadfish may eat Least killifish
Data used by the planner
| Temperature | 20–26 | AqAdvisor (aqadvisor.com), retrieved 2026-10-04; agrees with FishBase (fishbase.se), retrieved 2026-10-04 · medium confidence |
|---|---|---|
| pH | 7–8 | AqAdvisor (aqadvisor.com), retrieved 2026-10-04; agrees with FishBase (fishbase.se), retrieved 2026-10-04 · medium confidence |
| Hardness (dGH) | 5–15 | AqAdvisor (aqadvisor.com), retrieved 2026-10-04 · low confidence |
| Origin | Southeastern United States | curated-v0 (needs expert review) · low confidence |
| Beginner friendly | Yes | curated-v0 (needs expert review) · medium confidence |
| Care level | easy | curated-v0 (needs expert review) · medium confidence |
| Activity | moderate | curated-v0 (needs expert review) · medium confidence |
| Swimming level | middle | curated-v0 (needs expert review) · medium confidence |
| Temperament | peaceful | curated-v0 (needs expert review) · medium confidence |
| Nips fins | No | curated-v0 (needs expert review) · medium confidence |
| Long fins | No | curated-v0 (needs expert review) · medium confidence |
| Territorial | No | curated-v0 (needs expert review) · medium confidence |
| Lives in groups | No | curated-v0 (needs expert review) · medium confidence |
| Minimum group | 1 | curated-v0 (needs expert review) · medium confidence |
| Diet | omnivore | curated-v0 (needs expert review) · medium confidence |
| Lifespan (years) | 1–3 | curated-v0 (needs expert review) · low confidence |
| Months to adult size | 3 | curated-v0 (needs expert review) · low confidence |
| Safe with plants | Yes | curated-v0 (needs expert review) · medium confidence |