Overview

The American Flagfish is a striking and unique freshwater fish named for its resemblance to the U.S. flag, with its iridescent scales and red, blue, and white markings. It is a member of the killifish family and is known for its algae-eating habits, making it a great addition to planted aquariums.

Origin

Native to slow-moving waters, marshes, and ponds of Florida, USA, the American Flagfish thrives in warm, vegetated habitats with plenty of plant cover.

Feeding

American Flagfish are omnivores, with a strong preference for vegetation and algae. They readily consume:

Algae (a great natural grazer for planted tanks)

High-quality flake or pellet food

Blanched vegetables like zucchini and spinach

Live or frozen foods like brine shrimp, daphnia, and bloodworms for protein

Tank Mates

While generally peaceful, American Flagfish can be semi-aggressive, especially males during breeding. Suitable tank mates include:
 Small peaceful fish like tetras, rasboras, and corydoras
 Larger shrimp species and snails
 Other killifish or small livebearers

Avoid:
 Long-finned or slow-moving fish (e.g., bettas, fancy guppies) as they may nip at fins
 Extremely small or timid species that may be outcompeted for food

Aggression

Males can be territorial and aggressive towards one another, especially during spawning. It is best to keep either a single male with multiple females or a small group in a well-planted tank to diffuse aggression.

Experience Level

Intermediate – While hardy, they require a well-maintained, algae-rich tank and can be aggressive if not housed correctly.

Water Parameters

Temperature: 66–85°F (19–29°C)

pH: 6.5–8.5 (prefers slightly alkaline conditions)

Hardness: 6–20 dGH

Tank Size: Minimum 15 gallons for a pair, larger for groups