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Main Index > Detailed Fish Profiles > Cyprinids > American Flag Fish
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This page will give a completely detailed profile of the selected fish, from A to Z. The profiled fish will be chosen randomly by Badman, and will come from the complete genre of tropical fish. New profiles are added on a regular basis. If you would like to submit a profile for the site please contact me. Don't forget to let us know you experiences with this fish by filling out the

North America


American Flag fish

Jordanella floridae


    Seldom seen the American Flag fish is a fantastic algae eater and one of the easier Killifish to keep in your home. The males are beautiful and both are rugged and extremely tolerant of varied water conditions

Quick stats:


    Listed tank sizes are the minimum
    Size: Up to 2" (6 cm)
    Tank: 24 inches
    Strata: Bottom-middle
    PH: 6.7-8.2
    Hardness: Hard and alkaline. dH range: 6.0-20.0°
    Temperature: 66-72°F (19-22°C)


    Order: Cyprinodontiformes
    Family: Cyprinodontidae
    Subfamily: Cyprinodontinae
    Genera: Jordanella
    Species: floridae

Ochlockonee River, Florida

Common name:

    American Flag Fish

Image gallery:

    Additional species photographs


    Badmans' Forum


    North America, Florida to the Yucatan Peninsula.

General Body Form:

    Short and stout and laterally compressed. The tail and dorsal fins are set back on the body. The males are larger.


    The male is a beautiful fish, the sides are an olive green and the back is tinted brown. The sides are dotted with rows of iridescent dots alternating between silver and red forming a pattern that resembles the stripes on a flag. The dorsal and anal fins are tinted yellow with additional rows of red dots. There is a dark black center spot located in the middle of the side. Under reflected light this pattern really shines. The females are not as colorful with sides having an drab yellow base color with checkerboard spotting. There is a large spot on the dorsal fin making it easy to identify the female.


    Easily cared for the flag fish is adaptable and can be housed in a small aquarium. To show off the colors best the tanks' substrate should be dark in color, heavily planted and well lit with some open areas for swimming. Preferring slightly cooler temperatures choose your plants accordingly. Rivaling the SAE in the ability to eat algae the Flag fish diet must include some vegetable matter like spinach or romaine lettuce in addition to a well balanced flake food. Morning sunlight to encourage algae growth is beneficial. Males are territorial so in a small tank only one should be kept. Timid and shy they must be comfortable with their surroundings and tankmates to fully show off their colors. Livebearers and Cory cats would make good choices. The type of filtration is not overly important, but proper tank maintenance must be routine.


    Found in still and slow-moving marshes, swamps, lakes and ponds.


    Easily bred, this is an excellent way to start out with breeding Killifish. The male prepares a small depression and lines it with tank debris. Over several days the female will lay her eggs averaging about 20 a day. There must be hiding places for the female during this process. Once the eggs are all laid it is best to remove the female. The male guards the nest much like the cichlids and will keep all others away. If the temperature has been raised to about 75ºF (24ºC) the eggs will hatch in five to ten days Very small they must be fed infusoria and other types of small food. After two weeks they should be transferred to another tank that is heavy with algae growth.


    American Flag fish
    American Flag fish


Your comments:


Please remember that the following comments are personal experiences and may or may not apply to your setup. Use them as guide to help better understand your fish, like us all individuals will behave differently under different circumstances.


From: Carola L.
Added one male in 29 GA tank with school of dwarf neon rainbows, Betta, GBR, and for a week he didn't eat anything. He schooled with the rainbows and hungout with the GBR. He swam against the glass a lot and didn't seem happy. So I got him a female and he started nibbling on algae immediately. They are so cute together and are quickly becoming one of my favorite fish.
From: Kevin
I just put 4 flag fish in my community tank ( tetras ) The flag fish when threatened will play possum& swim as if it's dying, they turn very pale also. As soon as that threat is gone they swim correctly & regain all their color back., It is a funny thing to watch.
From: Paulo
I am an old timer with Killi's but lost interest for a few years. I set the tanks back up to raise plants and had been grumbling about algae for almost a year. Hair, green, blue green, you name it and I have had it! Last summer I "Inherited" a pair of Florida Flags and a couple of pair of Goodid's and tossed them in the garden pond hoping to make some bird happy. Much to my surprise and delight both species colored up till they were my favorite things in the pond. Plus they threw dozens of fry. I just brought them in and placed them in a very heavily planted 55 gallon tank that I was thinking of tearing down for algae issues. One week and I have Zero algae of any kind. The fish are happy and I am a convert. They have not eaten the milfoil or the val or the naja or much of the duckweed but they certainly went to town on the algae. My recommendation if you want to raise plants. Get a school of these fish for the tank fast!
From: BK
For what it's worth, I've had a couple handfuls of these fish in my koi pond in Southern California for a couple of years now. They seem happy and healthy. They almost always travel in schools (of just flag fish) except when it appears that one of them is defending a nest. I rarely put food in the pond, but when I do (small, pellet koi food), the flag fish will nip at it. Usually, however, I see them munching algae from the liner and planters. I'm not sure this sort of living condition is advisable in most climates in the states (certainly not colder climates), but I've seen the water temps in my pond go well into the 50's during the winter, yet the flags seem to be doing fine. My summer water temps are usually mid 70s. The pond also has mosquito fish, rainbow shiners, and koi. yummy.
From: Brian
I have not cracked the code on American FlagFish behavior but hope with enough time I will. What I can report is that its clear to me that the main issue is keeping them stuffed with food. A Flagfish thinks five minutes is a long time to go without food. Flagfish live in swamps where they can eat algae non stop. Periodic eating comes naturally to predators, but not to Flagfish. I have found that almost all aggression toward tankmates can be eliminated by keeping Flagfish well fed. Since my Flagfish are the only fish in my tank that feed at the surface I add freeze dried blood worms to the tank to feed the Flagfish alone. This keeps him full enough to stop him from being aggressive without having to overfeed the tank as a whole and end up with water quality problems. I want to add that I keep my Flagfish in a tank solely inhabited with fish native to the southeastern US. I don't think the problem is that Flagfish are incompatible with tropical fish. When my Flagfish is hungry I experience the same fin nipping and fish chasing others report. I think all of the harassment of other fish that Flagfish owners report is really incompetent hunting. This is the slowest fish I have ever owned. He doesn't even have that short burst of speed most slow fish normally have. I consider Flagfish the Elmer Fudds of hunting. Fin nipping was a serious problem for me until I decided to just keep adding freeze dried bloodworms everytime I saw the Flagfish chasing other fish. I am convinced most behavioral problems with this fish are due to its need for near constant eating. Inch for inch it is the most voracious eater I have encountered. Its a pretty fish, prettier than the pictures here and most pictures on the web. And its an active and interesting fish. I call mine Crazy Uncle because he is always doing something interesting even though its not always interesting in a good way. If you can keep their bellies full they are a good fish to have. I have found them to be picky about what algae types they will eat. But if they will eat it, they will eat it almost non stop. Same with plants, mine eliminated the duckweed from my tank. They are pickier than I see commonly reported, but if they like it the fish is a bottomless pit for that type of food. Worth noting that the fish is very hardy. Not a lot of work outside of the issues I've mentioned.
From: Cherna
Purchased six flag fish from an online dealer who shipped them poorly; the fish arrived in awful condition. When put in a planted 10 gal tank by themselves for awhile, they recovered completely. They are terrific at cleaning out hair algae, but be careful to put them in tanks with fine, feathery plants as they will graze them to death even if well-fed otherwise (my water milfoils have been completely destroyed). Moved to a larger tank with serpae tetra, tiger barbs, plecos, beta and oto catfish; I have 4 males and 2 females and all are well behaved. The males are so busy showing off to each other that they leave the females alone. No babies yet.
From: Larry
These are great fish, they are as predictable as ANY fish, I am amazed though when I read comments about people who find them aggressive , one person lost rainbows, another fantails ( but his guppies where fine). Who in their right mind would mix Asian coldwater fish with N.American fish, who would mix Tropicals with cold water, why have rainbows ( Australian ) with American fish. These fish come from different area, different climates, different water conditions, flow rates, ect. When you start taking a fish and putting it in a situation that is nothing like its normal habitat, it is not surprising to see odd ( even aggressive) behaviors ect. These are just fish, but they are really great fish and deserve to be kept in the correct environment, not just thrown in to an inappropriate tank as a tool to control algae. Well that's all,,, they're great fish and if you really want to enjoy them, give them their own tank.
From: J
I bought a female to handle some BBA in my planted tank, then picked up a male a few days later. One week after that, I have three dead rainbowfish. The male is very aggressive towards every species of rainbow I have in the tank. Separated the male and female, and the male continues to attack other fish that are 4-5 times larger than himself. If you want to get this fish, I would recommend you investigate if it is compatible with your fish or not.
From: Dennis
Just bought a male and female American flag fish in hopes of cleaning out some hair algae in a very thickly planted 44 gallon tall tank. The tank has several different species of plants including water wisteria, Java fern, lacy Java fern, Java moss, several anubias, amazon swords dwarf sagitaris, jungle and corkscrew val, and a few others like the bronze wendti... I have a total of 15 small fish in this tank including 2 cory cat fish, neon tetras, rasbora hets and otocinclis, and a few other tetra. So far its been a day and they have been just as effective as the three Siamese algae eaters I have in there in addition to the other fish I named. Till this current time the American flag fish are behaving themselves nicely and have actually been pleasant to watch. After a few minutes of putting them in the tank and giving them some time to check out their new surroundings they started swimming side by side with each other and other interesting things between meals of hair algae. I may try to post an update later when I see how things progress. So far my opinion is - good fish to have if you have a job for it to do especially
From: Stan
I have had one of these beautiful fish for several months now. I originally brought him home to clear off some algae from my plants but I have never seen him eat anything other than flake food or bloodworms. I recently bought 3 juvenile green severums and after about 3 weeks the severums have started harassing him. I'm seeing possible signs of ick so it's time to move him to quarantine...then to a milder tank.
From: Karen
I had two aquariums, very heavy with algae, especially hair algae that came with some plants. One is a 29 gallon with White Clouds and one male two female flag fish. The other is a 20 long with 3 mollies and one small yellow labrichromis and one male three female flags. Both tanks are well planted and use window sun light for most of the lighting needs. After putting the flags in both tanks they are nice and clear. Mine are so far peaceful, may have spawned a few times but any fry would be eaten in these tanks. Both tanks are unheated and depend only on the plants for filtration. Next I am going to set up a tank just for them to see if I can spawn and raise some fry.
From: Paul
These are the fish to get if you have hair algae. They eat hair algae for fun and cleared my tank up in a week.
From: Barry Robinson
I have 1 Male & 3 Female in a community tank. The Male is largest at approx. 1 inch. I has been very aggressive towards certain other fish in the tank, namely Fantails, which are 2-3 times its size. I have witnessed it chasing and nipping, ripping chunks out of the fishes tails and eyes. Due to this I have lost 2 out of 3 Fantails. However it does not seem to bother the minnows, Pleco's, or shrimp.
From: Jenny
Flag fish will mix well with most fish, but be careful; certain species will pick on them. The males are very pretty and more then one male can be in a school with out problems. These fish are hardy and aren't picky on water conditions. I've caught these fish in drainage ditches in central Florida. If you catch them in the wild make sure you quarantine them so you don't get parasites like Anchor Worm, Ick, and gill parasite. These fish like to school with there own kind.





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