American Flagfish

Jordanella floridae

Also known as: Florida flagfish, Flagfish

Water Parameters

• Temperature: 18–26°C
• pH: 6.5–8
• Hardness (GH): 89–268 ppm (5–15 dGH)

Values above are general hardness (GH). For carbonate hardness (KH), the buffer that keeps pH stable, see the water parameters guide.

Care Summary

A stocky little killifish from the swamps and ditches of Florida, named because the male's pattern, rows of red and metallic-green spangles over an olive body with a dark side-spot, was thought to recall a tattered version of the United States flag. Beyond the looks it has a genuinely useful trick: it is one of the handful of fish that will actually graze hair algae and even black beard algae, which makes it a rare clean-up option for cooler tanks. The catch is a feisty, territorial streak in the males, so it is best kept with more females than males and with sturdy, short-finned tankmates. Cool-tolerant, hardy, and undemanding, it is an underrated and practical fish for an algae-troubled temperate community.

Tankmates

A North American killifish kept as much for its appetite as its looks: it is one of the very few fish that genuinely eats hair algae and black beard algae. The trade-off is temperament. Males are territorial and a little nippy, especially when breeding, so keep more females than males and pair them with robust, short-finned tankmates rather than slow or long-finned fish. Its tolerance of cool water makes it a useful algae-cleaner for unheated or lightly-heated tanks where siamese algae eaters and otocinclus struggle. Avoid keeping it with dwarf shrimp, which it may eat. Provide some plant cover and open grazing surfaces.

Compatible with

• White Cloud Mountain Minnow
• Gold Barb
• Rosy Barb
• Zebra Danio
• Bronze Corydoras
• Bristlenose Pleco
• Peppered Corydoras

Avoid keeping with

• Betta
• Long Finned Species
• Guppy
• Neon Tetra
• Cherry Shrimp

Common Problems

• male territoriality and fin nipping, especially when breeding
• predation on dwarf shrimp
• needing more females than males
• stress when kept too warm long-term

Sources: seriouslyfish.com, fishbase.org · Last updated: 2026-06-20