MS Livebearers

Heterandria Formosa Info

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Some information on the world's smallest livebearer!

Heterandria Formosa


Least killifish

World’s Smallest Livebearer


Heterandria formosa is the only member of its genus to be found in the United States. The formosa’s range covers southeastern United States, ranging from South Carolina down to Georgia and Florida, and through the Florida Gulf Coast to Louisiana. It is one of the few aquarium fishes to come from North America.

The formosa lives primarily in vegetated, slow moving or standing freshwater but also occurs in brackish waters

Size: females: 3 centimeters (1.2 inches), males: somewhat smaller at about 1.5-2 centimeters (0.8 inches)

pH: 7.0-8.0

Temperature: 68F - 85F (22C - 28C)

Tank Size: 10 gallons or larger

Tank Range: Top, Middle, Bottom

Care: Since they are omnivorous, the formosa will generally eat all kinds of live, fresh, and flake foods. To keep a good balance, give them a high quality flake food everyday.  You can feed them brine shrimp (either live or frozen) or blood worms as a treat.

Sexing:  Both sexes show the same colors. They are brown bodied with a horizontal brown black stripe going from the mouth to the tail base. The stripe is intersected by vertical brown black stripes. The amount of striping usually varies from fish to fish. Some also have blotches in place of stripes on their backs.  The male is also slimmer and has a "straw" shaped anal fin called a gonopodium. The female has a fan shaped anal fin, is rounder of body.


Breeding: Livebearer: H. formosa females drop fry differently than other livebearers.  Rather than dropping the entire brood all in one day, females drop their young live 2 or 3 at a time daily for several days, and seem to be continuously pregnant. Although they don't guard their young, parents hardly ever try to eat them, so the fry are safe to raise in the same tank.


Murray, NE