American Flagfish (Jordanella floridae)

The American Flagfish (Jordanella floridae) wears its patriotism on its sides: rows of red and iridescent green scales down a stocky little body, with a dark shoulder blotch standing in for the field of stars. This is a true North American killifish, not a tropical import, and it is one of the hardiest beginner fish we stock. It shrugs off cool room temperatures, it breeds readily in a home aquarium, and it is one of the very few fish that will genuinely graze hair algae and black beard algae. Browse the rest of our freshwater livestock and supplies to build the tank around it.

Care Guide

• Tank size: 20 gallons minimum, and a 20 long beats a 20 tall. Floor space and plenty of sight breaks are what keep males civil with each other.
• Temperature: 65 to 85°F. They come from Florida marshes that swing with the seasons, so most rooms need no heater at all. That makes them a great pick for a basement tank or an unheated setup.
• Water parameters: pH 6.5 to 8.2, hardness 6 to 20 dGH. Genuinely adaptable, and hard tap water is no problem for them.
• Feeding: omnivore with a heavy vegetarian streak. Build the diet around algae based gels and veggie flakes like Repashy Soilent Green or Ocean Nutrition Spirulina Flakes, then add frozen or live foods a couple of times a week.
• Stocking: one male with two or three females is the classic setup. A larger group works in a 20 long or bigger as long as the aquascape is dense enough to break up sight lines. Two males in a small bare tank will spar nonstop.
• Algae duty: keep them a little hungry on protein and they will work the hair algae hard. A flagfish that gets stuffed with pellets every day has no reason to bother.
• Lid: required. Killifish jump, and this one is no exception.

Specifications

Compatibility

Pair flagfish with quick, short-finned tank mates that can get out of the way. Good matches include the Zebra Danio, Cherry Barb, Brilliant Rummy Nose Tetra, Boesemani Rainbowfish, and bottom dwellers like the Panda Cory or Orange Laser Corydoras, which stay below the action entirely. They also make good coworkers for the rest of the cleanup crew, including the Siamese Algae Eater, Otocinclus Catfish, and nerite snails such as the Batman Nerite.

Skip anything slow with long flowing fins. Fancy guppies, bettas, and long-finned varieties are exactly the profile a bored male flagfish will nip at. Full grown Amano Shrimp are usually fine, but assume any shrimplets become snacks. If you keep another killifish, our Clown Killifish is a nano sized cousin for a separate tank.

Recommended Foods & Supplies

• Repashy Soilent Green algae gel, the closest thing to their natural diet
• Repashy Super Green
• Ocean Nutrition Spirulina Flake Food
• Hikari Algae Wafers
• Two Little Fishies SeaVeggies Green Seaweed with a VeggieMag clip

FAQ

Will it actually eat hair algae?
Yes, and there is a very short list of fish you can say that about. The trick is restraint: go easy on the protein foods so they keep grazing. Treat them as one working member of the crew alongside manual removal and fixing whatever is feeding the algae, not as a magic fix.

Is the fish in the photo a male?
It is. Males carry the full flag pattern with red and green rows and a deeper body. Females are a softer olive and tan with a dark spot near the back of the dorsal fin. Let us know which you are after and we will do our best to net what you want.

Do I need a heater?
Usually not. They are comfortable anywhere from 65 to 85°F, which covers most homes year round. A cool room or an unheated basement tank suits them better than it does most tropicals.

Will they eat my plants?
They will graze soft, fine-leaved plants if the veggie side of their diet is thin. Feed greens regularly and lean on tougher species like Java Fern, Anubias, and Java Moss, and you will not have a problem.