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No federal permit to keepFlagfish
Jordanella floridae
Fishes › Killifish and livebearers (Cyprinodontiformes) › Cyprinodontidae (Pupfish)
The flagfish (Jordanella floridae), also known as the American flagfish or Florida flagfish, is a species of pupfish, a type of killifish from the family Cyprinodontidae which is endemic to Florida.
Care at a glance
Species-specific aquarium care
- Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 2.4 in / 6 cm).
- Water: Freshwater (tolerates brackish).
- Temperature: 64–72°F (range recorded for this species).
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Diet: Eats a varied diet: mix quality prepared foods with frozen and live foods. FishBase classes it as a omnivore.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 24 × 12 in (roughly 14 US gallons); space needed is rated “modest tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 64–86 °F, pH 6.5–8.5, 2–20 dGH.
- Behaviour: a shoaling fish best kept in a group of six or more; not a community fish.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Need not be too complicated so long as there are plenty of broken lines-of-sight.”
- Diet: “Chiefly a micropredator feeding on small aquatic crustaceans, worms, insect larvae and other zooplankton although algae and other plant material is taken as well.”
- Tankmates: “Best-maintained alone, especially if the intention is for the fish to breed, but can be maintained in a well-researched community provided sufficient space is available.”
- Breeding: “Contrary to many reports, including a number of scientific papers, this species breeds in the same way as other cyprinodontids and does not dig pits or exhibit extended parental care.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Pupfish
Applies to most species in this group. Habitat: These fish occupy shallow vegetated fresh or saline waters, ranging from Florida marshes to coastal lagoons and the isolated Devils Hole pool. [fg179-flag, fg179-sheep, fg179-fws]. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- For a flagfish pair, use at least a 60 × 30 cm footprint; groups need more room.
- Break sightlines with plants or spawning mops to provide cover between territorial males.
- Use sponge filtration when eggs or fry are present.
- Encourage filamentous algae for flagfish grazing.
- Flagfish: pH 6.5–8.5 and 2–20 dGH; establish species and population requirements before choosing fresh or saline conditions.
Climate & lighting
| Water | 64.4–86°F |
Diet
- Algae or an algae-containing prepared food for flagfish.
- Small live or frozen Artemia and Daphnia.
- Small bloodworms and other appropriately sized invertebrate foods.
Social life
- Flagfish males form territories; keep groups only with sufficient cover and space. Species-only maintenance is preferable for breeding.
Health watch
- Aggression injuries under overcrowded conditions; a general aquarium-fish risk.
- Ammonia-associated gill damage in inadequately cycled systems.
- Skin parasites or secondary bacterial infections introduced with new fish.
Understanding the animal
About this animal
About this animal
It is found in the aquarium trade. Its common name derives from the dominant males' body pattern, which bears some resemblance to the flag of the United States.
Quoted from the Wikipedia article “Flagfish” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater and brackish water, in rivers and streams, lakes, estuaries. Uses both the bottom and open water. In vegetated sloughs, ponds, lakes, and sluggish streams; enters brackish water. 6.5 cm max TL. |
| Water it lives in | Freshwater / brackish water, 64–72 °F (18–22 °C). |
| Climate | Subtropical climate. |
| Behavior to plan for | Breeding: nesters, paternal parental care. |
What this means for care
- Keep water within its wild range, 64–72 °F.
- It tolerates or needs brackish water; check salinity needs before setup.
- Parents guard eggs or young, so expect territorial behavior when breeding.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 91°F (up to 92°F in the hottest sampled areas) |
| Cool-season lows | about 49°F (down to 41°F in the coldest sampled areas) |
| Average temperature | 68–75°F across sampled records |
| Relative humidity | 72–73% on average (driest month about 68%) |
| Rainfall | about 1295 mm a year |
Measured at 103 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | The flagfish (Jordanella floridae), also known as the American flagfish or Florida flagfish, is a species of pupfish, a type of killifish from the family Cyprinodontidae which is endemic to Florida. It is found in the aquarium trade. Its common name derives from the dominant males' body pattern, which bears some resemblance to the flag of the United States. — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Reproduction | Males care for the eggs. Lays up to 100 eggs in the aquarium. The male does a 'T-dance' with a receptive female and the female lays her eggs over algal-covered rocks where they adhere by their sticky thread. — FishBase |
| Appearance and size | Flagfish are small, robust fish, 6 cm in length, with a truncated snout which has been compared to that of a bulldog. They have rounded fins with the dorsal and anal fins positioned posteriorly and adjoining the caudal fin. Females have an obvious spot on their flanks and a clear spot near the posterior end of the dorsal fin, this has an opaque white margin. — Wikipedia (community-edited) |
| Biology | Adults are found in vegetated sloughs, ponds, lakes, and sluggish streams. They enter brackish water. They feed on worms, crustaceans, insects and plant matter. — FishBase |
| History and naming | The flagfish was described by George Brown Goode and Tarleton Hoffman Bean in 1879 with the type locality given as Lake Monroe, Florida. The generic name honours the American ichthyologist David Starr Jordan (1851–1931). It is closely related to the Yucatan flagfish Garmanella pulchra which is sometimes also placed in the genus Jordanella. — Wikipedia (community-edited) |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Adult length
Maximum recorded length. Measured as total length. Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
pH
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 24 × 12 in (about 14 US gallons).
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Seriously Fish: Jordanella floridae Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- FishBase: Cyprinodon variegatus Peer-reviewed researchAdded in the 2026 source-checked care-guide review.
- US Fish and Wildlife Service: Inside Devils Hole Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual: Disorders and Diseases of Fish Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.
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