Max Size: 7cm

American Flagfish (Jordanella floridae)

The American Flagfish are reasonably peaceful apart from when they are nesting. They can become very territorial even towards the female, and individuals can also be bad-tempered fin-nipping bullies. Therefore, if you keep them in a community aquarium, you will need a relatively large and spacious one with plenty of hiding places; this should limit any problems if they choose to spawn.

Any aggression is generally aimed towards their own kind. Still, if these fish are given sufficient room and have plenty of visual barriers amongst the plants and decor, this should not become an issue.

American Flagfish is best kept in a species only aquarium; however, if you do choose to house them with other fish, then their tankmates should be of similar temperament and size and will need to be able to live in the same cooler, slightly alkaline conditions as the Flagfish.

Flagfish are small, hardy, robust fish with a lopped snout that has been compared to that of a bulldog. They have rounded fins with the anal and dorsal fins positioned posteriorly and adjoining the caudal fin. Females have a prominent spot on their flanks and a transparent spot near the posterior end of the dorsal fin; this has an opaque white margin.

The fins may show a slightly reddish colour, but this can come and go in individuals, although the reason for this is unknown. The female's body is mainly olive, just marked with turquoise scales.

The American Flagfish get its name from the male during the breeding period due to the remarkable resemblance of the stars and stripes on the United States flag. The male also has a dark spot positioned at the lower rear corner of the dark rectangle.

Quick Facts
Scientific NameJordanella floridae
Other NamesFlagfish, Florida Flagfish
Aquarium LevelMiddle - Top
DifficultyBeginner - Intermediate
Best kept asTrios
Lifespan2 - 3 years
Water Parameters
Water TypeFreshwater
PH6.5 - 8.5
GH5 - 20
TDS36 - 357
64 - 86℉
17.8 - 30℃


American Flagfish Male
Male American Female
Male American Female
Female American Flagfish

Natural Habitat

American Flagfish is endemic to Peninsular Florida South of the Ochlockonee and St Johns River Basins in the United States. These fish inhabit shallow, heavily vegetated still to slow-moving freshwaters such as ponds, lakes, backwaters, floodplains, marshes, canals, ditches and streams but have occasionally been observed in slightly brackish water.


American Flagfish will mainly graze on any available algae in the aquarium. However, if there is not enough algae for your fish, supplement this with high-quality dried foods such as flakes, pellets or algae wafers, alongside live and frozen foods such as brine shrimp, white worms, tubifex, daphnia and bloodworm. It would also be beneficial to your fish if you provided them with the occasional treat of blanched vegetables such as zucchini or spinach.

Sexual Dimorphism

It is pretty easy to differentiate between male and female American Flagfish. Adult males hold more extended anal and dorsal fins and are significantly more colourful than females, more so when in spawning condition. In contrast, adult females are typically rounder-bellied than males, especially when gravid, and occupy a dark blotch on the posterior part of the dorsal fin that is not present in males.


American Flagfish is fractional Spawners, meaning females release eggs at intervals over a period when warm temperatures are sustained. However, ideally, they should be permitted to breed on a seasonal basis in spring and late summer as they would do in nature.

The males will form temporary territories which they will defend against rivals while attempting to lure females into spawning; dominant individuals will display more intense colouration.

The eggs will be released singly or in small batches and attached to algae or other surfaces using tiny threads. Neither male nor female show any parental care towards their eggs once they have been deposited.

While some eggs may get eaten if left with the parents, this species isn't incredibly insatiable. If plenty of plant cover is present, the fry will appear in with the adults. However, the most productive method is to remove the eggs and hatch them in a separate grow out tank containing water of the same temperature and chemistry as that of the adults.

The incubation period is temperature-dependent, although generally, it takes between 7 to 14 days. You should initially offer the fry green water or infusoria, moving on to microworm and artemia nauplii when they become free-swimming.

Unfortunately, the larger-sized babies will not hesitate to eat their smaller siblings, so it would be better if you separated the fry by size if some grow more quickly than others.

Other Killifish of interest

Blue Striped Rivulus Killifish(Rivulus Xiphidius, Laimosemion xiphidius)
Bluefin Notho(Nothobranchius rachovii)
Clown Killifish(Epiplatys annulatus)
Eggers Killifish(Nothobranchius eggersi)
Lyretail Killifish(Aphyosemion australe)
Mamou Killifish(Scriptaphyosemion guignardi mamou)
View all Killifish
Date Added: 05/05/2021 15:00:55 - Updated: 19/01/2022 14:32:34