Least Killifish (Heterandria formosa)


World’s smallest Live Bearer!

Out of stock

SKU: leastkilli Category:




Diet: Unfussy Omnivore, eats flake, worms, daphnia, and even pleco bark!
Social behavior: Congregates loosely.
Origin: Tank-bred, but indigenous to North America (Florida to Louisiana)
Average adult size:
Lifespan: 3+ years


Temperature: 72° - 84° F (22° - 29° C)
PH: 6.0 - 9.0, tank-raised specimens are more flexible regarding pH level
Minimum tank size: 5 gallons for a trio, but a larger tank is required for a group. Prefer slower moving water. Stay away from power heads.

What I Love About This Fish:

  • Smallest live bearer, pregnant with 1.5 babies!
  • Hardy with plenty of personality
  • Possible to breed in the aquarium
  • Compatible with many other species in a spacious tank


This striking live bearing fish, Least Killifish (Heterandria formosa) is a native fish to the United States!  They are currently among the smallest live bearers on the planet! In fact, the females reproduce differently than most live bearers.  Females carry one baby to full term and one baby about half way! This means that females will have one baby a day, every day.  The babies live in the tank into adulthood with no special food or care.

Please see above for availability!

Least Killifish (Heterandria formosa) will thrive in any aquarium with a peaceful tankmakes with any substrate choice.  This is an excellent candidate for a planted tank with shrimp.  This fish does not tend to eat dwarf shrimp and other small, delicate invertebrates.

Feeding the Least Killifish (Heterandria formosa) is simple for this unfussy eater. High-quality dry, frozen, and live meaty foods are an excellent choice of diet.  A quality and varied diet is key to keeping Least Killifish (Heterandria formosa) looking its best.


Additional information

Weight 16 oz
Dimensions 8 × 8 × 8 in