🐟TankstockerFreshwater Stocking & Compatibility

🐠 Least Killifish Heterandria formosa

Least Killifish (Heterandria formosa) — male
Male
Least Killifish (Heterandria formosa) — female
Female

The Least Killifish (Heterandria formosa) is a easy-care, peaceful species from Southeastern United States. Adults reach roughly 1.2", so plan on a minimum tank of 5 gallons. Keep the water between 66–79°F with a pH of 7–8. This is a schooling fish — keep a group of at least 3 so it feels secure and colors up. As an omnivore, it does best on a varied diet appropriate to its feeding style.

At a glance

Adult size1.2"
Minimum tank5 gallons
Temperature66–79°F
pH7–8
TemperamentPeaceful
SchoolingYes — group of 3+
DietOmnivore
Care levelEasy
OriginSoutheastern United States
Shop 5-gallon setupsFilterWater test kit

Good tankmates for Least Killifish

Neon TetraRummynose TetraSerpae TetraGuppyEndler's LivebearerPlatyGerman Blue RamZebra DanioHarlequin RasboraChili RasboraCherry BarbTiger BarbWhite Cloud MinnowBronze CoryPanda CoryOtocinclusCherry ShrimpAmano ShrimpNerite SnailMystery SnailMarble HatchetfishEmber TetraBlack Neon TetraLemon TetraGlowlight TetraBloodfin TetraDiamond TetraBuenos Aires TetraEmperor TetraSilver Tip TetraX-Ray TetraCelestial Pearl DanioLambchop RasboraPearl DanioGlowlight DanioOdessa BarbCheckerboard BarbFive-Banded BarbNeon Dwarf RainbowfishThreadfin RainbowfishCelebes RainbowfishHoney GouramiSparkling GouramiMultifasciatusPygmy CorySterbai CoryJulii CoryHillstream LoachGhost ShrimpAssassin SnailRamshorn SnailMalaysian Trumpet SnailGold TetraPenguin TetraRed Eye TetraFlame TetraColombian TetraGalaxy RasboraPhoenix RasboraEmerald Eye RasboraLeopard DanioGold Ring DanioRuby BarbMelon BarbForktail Blue-eyeCroaking GouramiPeaceful BettaGolden RamYellow Dwarf CichlidShell-DwellerAlbino CoryThree-Striped CoryAdolfo's CoryHabrosus CoryZebra OtoDwarf Chain LoachBlue Dream ShrimpYellow ShrimpBlack Diamond ShrimpBumblebee ShrimpLyretail KillifishClown KillifishHigh-Fin PlatyAmerican FlagfishIndian Glassfish

Avoid these tankmates

Betta (male)AngelfishDiscusConvict CichlidOscarPictus CatfishParadise FishJack DempseyGreen TerrorTexas CichlidDemasoni CichlidAuratus CichlidFrontosaChinese Algae EaterRed Tail SharkFigure-8 PufferBlack Ghost KnifefishAfrican Butterfly FishRopefishSenegal BichirGolden Wonder KillifishBucktooth TetraBanjar Red CichlidSalvini CichlidMidas CichlidFlowerhornRed Zebra CichlidVenustus CichlidLivingstonii CichlidCompressed CichlidCalvus CichlidTropheus DuboisiRed Claw Crab

See the full tankmate guide for Least Killifish →