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Encyclopedia / Killifish / American flagfish
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Variations

1 kinds · tap one for a closer look

American flagfish

Jordanella floridae · Flagfish, Florida flagfish, Jordanella

Males are territorial and aggressive toward each other and sometimes fish in the nest area.

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6.5 cmBody length, without tail ✓
18–28 °CTemperature ✓
7–8pH ✓
54 LSmallest tank ✓
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Tank mates
Check your own mix →
Not recommended
  • Giant gourami eats animals up to about 10 cm. American flagfish only grows to 6.5 cm.
Not recommended
  • Oscar eats animals up to about 12 cm. American flagfish only grows to 6.5 cm.
Not recommended
  • Jack Dempsey eats animals up to about 8 cm. American flagfish only grows to 6.5 cm.
With conditions
  • Only a narrow pH range suits both: exactly 7.
With conditions
  • Only a narrow pH range suits both: exactly 7.
Compatible
Compatible
Compatible
Compatible
Compatible

343 species in our list are a good match.

Facts checked against sources on 16 Oct 2026. ✓ means a source backs it; ? means no reliable source yet. See sources

Care and water

Hardness ✓2–20 dGH
Group size ?3 or more
Temperament ✓Semi-aggressive
Swims at ?Middle
Care level ✓Moderate
Diet Herbivore
Lifespan ?Unknown
Size in shops 3–5 cm
Growth Medium

Behavior

Males are territorial and aggressive toward each other and sometimes fish in the nest area. Keep with equally sturdy tankmates.

Food

Algae, spirulina flakes, vegetables and frozen foods.

Tap a food to see what it is.

Male or female

Males are much more colourful, with longer dorsal and anal fins. Females are rounder-bellied and have a dark blotch at the back of the dorsal fin, which males lack.

Health

Common problems. Tap one to see the signs. This is a guide, not a diagnosis.

Breeding

Egg scatterer · Easy

A continuous (fractional) spawner: eggs are attached singly or in small batches to algae, plants or mops, and parents give no further care. Remove eggs to a separate tank for best yields.

Pairing

One male with 2-3 females.

Setup

Planted 60 L tank with a cave, flowerpot or spawning mop for each female.

What starts it

Warm water and a well-fed pair.

Eggs

Eggs are laid a few at a time over many days (up to about 100 in the aquarium); they hatch in 7-14 days depending on temperature.

Raising the fry

Baby brine shrimp and powdered flake; fry are easy.

Common mistakes
  • Not enough cover
  • Keeping males together
  • Cold water
Full breeding guide, day-by-day plan and simulator →

Where it lives in the wild

RegionFlorida peninsula, USA
Rivers and lakesLake Okeechobee, the Everglades and Florida's St. Johns River system
HabitatShallow, weedy marshes, ditches and lake edges
Native rangeAbout 350 km across
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The story of the american flagfish

A Florida pupfish that eats algae as well as small invertebrates. It is a long-standing aquarium favourite, now mostly commercially bred.

Goode and Bean described the American flagfish in 1879, and its genus was named after David Starr Jordan. Its red stripes on a blue-green body reminded people of the US flag, giving it its common name. It became a popular aquarium fish because it eats soft algae and the male guards the eggs.

First described by George Brown Goode & Tarleton H. Bean in 1879. Named for Genus Jordanella honours ichthyologist David Starr Jordan.

  • The male guards and fans the eggs until they hatch.
  • It is one of the few killifish that grazes on algae, including hair algae.
  • Its red-striped pattern is said to resemble the American flag.

Sources

16 facts checked with sources