The American flagfish is a highly sought-after species of fish originating from Florida. Also known as the Florida flagfish, or simply flagfish, it is a killifish, from the Cyprinodontidae family, which is only found in Florida. Its name comes from the color patterns on the males of the species, which bears a resemblance to the United States flag.
Male American flagfish have a dark rectangle on their shoulders (seen as the stars from the upper corner of the flag) and stripes along their sides. These stripes are usually red, blue, or orange, but sometimes pale green. The dominant male of the school will have the most vibrant colors, while the nondominant males, females, and juveniles will be more olive-grey.
Flagfish are endemic to Florida, only found south of the drainage basins of the Ochlockonee River and St. Johns River. Their native habitat includes well-vegetated backwaters, marshes, canals, and ditches. They have also been known to live in slightly brackish water as well.
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American Flagfish Care
The American flagfish is a sought-after species by many aquarists who are looking for something special for their tank. Generally not found in local pet stores, they are worth the extra effort needed to find one.
Are American Flagfish Easy to Care For?
As the American flagfish are quite adaptable to different water conditions in the wild, they are relatively easy fish to care for. They aren’t overly sensitive to water conditions or environments, and they have a wide-ranging diet. This makes them ideal for both new and experienced aquarists. Since American flagfish are known to be voracious algae eaters, they are also great for helping to keep the algae manageable in their tanks.
American flagfish are quite hardy, and therefore have a wide range of water temperatures they are comfortable in. Their water temperature can be anywhere in the range of 64-85° F (18-29° C). Although they are comfortable in the entire range, their optimal temperature is between 64-72° F (18-22° C).
Water pH and Hardness
The ideal water hardness for American flagfish is between 6.5 to 8.5, while the water hardness should be between 6-20 dGH.
American Flagfish Size
In captivity, American flagfish will grow to a maximum size of 2 to 2.5 inches, roughly 5 to 6.5 cm in length.
In the wild, they are known to grow slightly larger, up to 3.5 to 4 inches, approximately 9 to 10 cm.
Food and Diet
American flagfish are known for their voracious appetites, as they’ll eat whatever is offered to them. In their natural habitat, they are omnivores and feed on many different sources of food including insects, crustaceans, and algae.
In an aquarium, American flagfish are famous for feeding on algae, especially hair algae. If your fish are eating the algae faster than it can grow, algae-based fish food can be purchased at pet stores. Algae wafers are a great choice. If they aren’t getting enough algae in their diets, they will often start to eat any plants in their tank.
Vegetables should also be offered from time to time if you find your fish are starting to nibble at your plants. Zucchini, cucumber, peas, and carrots are some of their favorites.
Their diets should also be supplemented with freeze-dried, frozen, or live brine shrimp, bloodworms, or blackworms.
American Flagfish Lifespan
Most American flagfish have a lifespan between 2 and 3 years in an aquarium, although with exceptional care they have been known to live for as long as 5 years.
In the wild, there have been reports of them living for up to 8 years, although it is quite rare for them to get this old.
American Flagfish Tank Size
The recommended tank size for a pair of American flagfish is 20 gallons (75 liters). They do best in groups of 6 or more though, so keep this in mind and adjust your tank size accordingly.
American flagfish can also be kept in outdoor ponds, although you won’t be able to enjoy their spectacular colors nearly as well as in a tank.
American Flagfish Tank Setup
American flagfish aren’t overly picky when it comes to tank setup, so there are many different ways their tanks can be configured.
The substrate you choose can be either gravel or sand, as flagfish are ok with either. A lot of aquarists with American flagfish use a black substrate. This can be a bit more expensive, but the colors of your fish will look even more vibrant against it. If you are planning on breeding your flagfish, choose a finer substrate, as fry can get stuck if there are large holes for them to get into, such as with gravel.
American flagfish tanks should also have lots of plants, rocks, and driftwood in them. This not only helps to recreate their natural environment, but it also helps to disperse the aggression in your tank. If two males can see each other easily, they are liable to get aggressive with each other. Having lots of places to hide and break up sight lines is very effective in controlling this issue.
Flagfish live in waterways that have little to no current, so an air-powered sponge filter is recommended. This will make them most comfortable, as it will keep the water clean without adding too much water movement into their environment. American flagfish don’t generate too much waste when compared to other fish, so a sponge filter should provide more than enough filtration.
LED lights are recommended for your aquarium, as they will significantly enhance the looks of any plants in the tank by creating a shimmering effect when the rays from the light filter through the moving water. Ensure the tank gets direct sunlight from time to time to help enable algae growth. Make sure there isn’t sunlight on the tank all the time though, as flagfish don’t like to be exposed directly to sunlight for long periods of time.
American Flagfish Breeding
In ideal conditions, American flagfish will breed without any outside interference. If your flagfish are in a community tank, it is recommended to place them in their own tank for spawning. This will help the fry avoid getting eaten shortly after they hatch.
American flagfish are in the Guinness Book of World Records for being the fish that lays the fewest number of eggs. In the wild, the female will only produce about 20 eggs over a few days. In captivity, they will often lay many more eggs than in the wild.
How do American Flagfish Breed?
American flagfish are one of the easiest killifish to breed and often won’t require much extra effort on your part if the conditions are right for them. If healthy, they will often breed twice a year, once in the spring and again in the late fall/early winter.
If you are setting up a separate breeding tank (which is recommended to help get the most fry to hatch) choose one that is at least 24” long, but not too deep. The water conditions should be comparable to the main tank, except for the water temperature. It should be closer to the top end of the desired range in the breeding tank. Use an air-powered filter in the breeding tank as well, with a fine substrate. Floating plants should be provided to give cover, and also to create potential breeding spots. Decorations in the tank should be kept to a minimum during breeding.
Before they begin breeding, make sure to keep a close eye on the pair. If the male is ready but the female isn’t, he can be quite aggressive towards her, to the point of harming her reproductive organs. There needs to be adequate cover for the female to hide, or a clear partition can be put up in the tank until both fish are ready. If you use a partition, it can be removed once both fish begin to dance with each other at the partition.
When ready to breed, the males will set up their own territories, and then entice the females into them. Once the female approaches, they will begin a dance that signals the start of the breeding process. After mating, the female will lay the eggs on the plants in the tank, or in a slight depression in the substrate. She will likely lay small batches of eggs for a few days in a row, and they should be immediately removed from the breeding tank. Not only can the females eat the eggs, but the male flagfish can become quite aggressive toward her while defending the eggs.
If the eggs were deposited in a depression in the substrate, the male flagfish will protect the eggs against predators by fanning them with his pectoral fins, like many cichlid species are known for. The eggs will hatch in 7-10 days depending on the water temperature, at which point the male should be removed from the tank as well.
Once the fry hatch, they must be able to get to the surface of the water relatively easily. If they are unable to, a large number of them will likely die quickly. It is believed to be caused by their swim bladder development, and this is the reason your breeding tank should be fairly shallow.
Fry can be fed green water/infusoria at first, followed by baby brine shrimp once they get a bit larger. If some fry are growing faster than others, remove them and place them in another tank, as they will eat all the smaller fry given the opportunity.
How to Tell the Difference Male and Female American Flagfish
The easiest way to tell the difference between a male and female American flagfish is their coloration. The males have greener bodies, with much brighter markings. Female flagfish have a yellow coloration on their bodies, and also have a dark spot on their dorsal fins that the males of the species don’t have.
Male flagfish are also the larger of the two sexes, although female flagfish usually have more plump bodies than males.
American Flagfish Diseases
American flagfish are quite hardy and aren’t very vulnerable to most freshwater diseases that can plague other fish. They are, however, susceptible to bacterial or parasitic infections.
If you notice white lumps under their skin, that is a sign of an infection. Remove the infected fish from the tank immediately to prevent any further spread. Clean your main tank as thoroughly as possible, and keep a close eye on the remaining fish. Treat the infected fish with products such as Praziquantel (Prazi), or other treatments meant for parasitic infections.
American Flagfish Tank Mates
American flagfish are known for their tranquil nature, which can make them a great choice for a community tank. However, they don’t get along with all kinds of fish, so some caution is recommended when choosing tankmates for your American flagfish.
American Flagfish and Goldfish
American flagfish and goldfish can be good companions, as they have similar temperaments. It should be kept in mind though that the goldfish will grow considerably larger than the flagfish. As long as there is sufficient space and cover though, they can be great tank mates.
American Flagfish and Bettas
Since bettas have large, flowing fins and aren’t very fast, they aren’t great tank mates for American flagfish as they could get nibbled on.
American Flagfish and Shrimp – While some aquarists do have limited success combining shrimp and American flagfish, most recommend against it. Flagfish eat crustaceans in the wild, so sooner or later they are going to start to eat your smaller shrimps. If your tank has larger, peaceful shrimp, they may be okay with flagfish. Make sure the shrimp has lots of cover it can get too easily if the flagfish does get aggressive.
Other Tank Mates – As American flagfish can be a bit aggressive, it is recommended that any other fish added to their tank be both a fast swimmer and also not have long, flowing fins. Tetras, swordtails, or danios are all great choices.
Are American Flagfish Aggressive?
American flagfish are considered semi-aggressive. They can live with some other fish peacefully, provided there is lots of cover.
Are American Flagfish Fin Nippers?
American flagfish do tend to be aggressive fin nippers, so their tank mates should be fast-swimming fish to avoid getting nipped too much.
Are American Flagfish Good Community Fish?
As long as they are paired with other species that are of similar temperament, American flagfish can make great community fish, both in an aquarium, or a pond.
Are American Flagfish Schooling Fish?
American Flagfish is a schooling fish that enjoys the company of at least a few other fish in their aquariums.
How Many American Flagfish Should Be Kept Together
Depending on the size of your tank, the ideal number of American flagfish is 6, with no more than 2 males. Provided there is enough cover, there shouldn’t be any aggression issues in a school this size. Larger schools can be kept together, as long as the tank size is adjusted accordingly, and the male-to-female ratio is kept the same.
Where Can I Buy American Flagfish?
While most pet stores won’t have American flagfish in stock, there are a lot of online options for purchasing some fish for your aquarium. A quick online search should turn up multiple suppliers across the country to order from.
American Flagfish Price
Depending on where you purchase them from and their size, American flagfish can range in price from roughly $5 – $15 US. Some suppliers offer a bit of a discount if you order multiple flagfish together.