Least Killifish

Least Killifish

Heterandria formosa

💧 Freshwater ✌️ Peaceful 🟢 Easy 🍽️ Omnivore Schooling (4+)

One of the smallest fish in the world. Native to the southeastern USA. A livebearer despite the killifish name.

Tank Size

5 gal
minimum (10+ preferred)

Temperature

66–80°F
19–27°C

pH Range

6.5–8
water acidity

Max Size

1"
2.5 cm

Lifespan

2–3 years
typical in captivity

Swim Level

Top
preferred zone

Care Notes

Perfect for nano tanks. Very peaceful and easy to breed.

Feeding

Micro foods, crushed flakes, baby brine shrimp.

Compatible Tank Mates

Neon Tetra 1.5" Cardinal Tetra 2" Rummy Nose Tetra 2" Ember Tetra 0.8" Glowlight Tetra 1.5" Harlequin Rasbora 2" Chili Rasbora 0.7" Celestial Pearl Danio 1" Zebra Danio 2" Bloodfin Tetra 2" Lemon Tetra 1.5" Black Neon Tetra 1.5"

Use Caution With

Black Skirt Tetra 2.5" Serpae Tetra 1.75" Congo Tetra 3.5" Buenos Aires Tetra 3" Green Neon Tetra 1" Scissortail Rasbora 3.5" Silvertip Tetra 2" Phoenix Rasbora 0.8" Colombian Tetra 2.5" Giant Danio 4" Blue Tetra 2.5" Spotted Headstander 3.5"

Incompatible With

White Cloud Mountain Minnow 1.5" Angelfish 6" Oscar 14" Discus 8" Firemouth Cichlid 6" Jack Dempsey 10" Convict Cichlid 5" Green Terror 8" Severum 8" Blood Parrot Cichlid 8" Electric Blue Acara 6" Texas Cichlid 12"

Check Compatibility

Want to check if Least Killifish is compatible with a specific fish? Use our compatibility checker to build your complete tank.