RSS Facebook Twitter YouTube




Jordanella floridae GOODE & BEAN, 1879

Florida Flagfish

SynonymsTop ↑

Cyprinodon floridae (Goode & Bean, 1879)


Jordanella: named in honour of ichthyologist and founding president of Stanford University David Starr Jordan (1851-1931).

floridae: named for the state of Florida, United States.


Order: Cyprinodontiformes Family: Cyprinodontidae


Endemic to peninsular Florida in the United States, south of the Ochlockonee and St. Johns river basins and does not occur in Mexico.

Type locality is ‘Lake Monroe, Florida, U.S.A.’, one of numerous lakes within the St. Johns drainage.


Mostly inhabits shallow, weedy freshwater habitats including backwaters, marshes, canals and ditches and has occasionally been recorded in lightly brackish water.

Maximum Standard Length

50 – 55 mm.

Aquarium SizeTop ↑

An aquarium with base dimensions of 60 ∗ 30 cm or equivalent is just about acceptable for a single pair but like most members of the family Cyprinodontidae this species does best when maintained as a group in a larger tank or container.


Need not be too complicated so long as there are plenty of broken lines-of-sight.

Provide plenty of cover in the form of aquatic plants, wool mops, etc., and if using filtration air-powered, sponge-type units are best as these will not harm eggs or fry.

Lighting is unimportant but can be used if you wish, and growth of filamentous algae should be encouraged if possible.

Water Conditions

Temperature18 – 30 °C

pH6.5 – 8.5

Hardness36 – 357 ppm


Chiefly a micropredator feeding on small aquatic crustaceans, worms, insect larvae and other zooplankton although algae and other plant material is taken as well.

In the aquarium dried foods are accepted in most cases but regular meals of small live or frozen fare such as Artemia, Daphnia or bloodworm should also be offered.

If the aquarium or container doesn’t contain filamentous algae introduce a good quality dried product with added vegetable, ideally algal, content to the diet.

Behaviour and CompatibilityTop ↑

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.

Individual males require space to form territories but in most cases two or more can be kept in the same aquarium.

Sexual Dimorphism

Adult males possess more-extended dorsal and anal fins and are significantly more colorful than females, more so when in spawning condition.

Adult females tend to be rounder-bellied than males, particularly when gravid, and possess a dark blotch in the posterior portion of the dorsal-fin which is not present in males.


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.

It’s a fractional spawner with females depositing eggs on a more-or-less continuous basis when a warm temperature is maintained though ideally it should be permitted to breed on a seasonal basis in spring and late summer as it would in nature.

Males form temporary territories which they defend against rivals while attempting to entice females to spawn, dominant individuals showing more intense colouration.

Eggs are released singly or in small batches and attached to algae or other surfaces by means of small filaments, and there is no additional care from either male or female once they’re deposited.

While some may be eaten if left in situ this species isn’t especially voracious and if plenty of cover is present fry will appear in with the adults although the most productive method is to remove the eggs and hatch them in a separate tank containing water of the same chemistry and temperature as that of the adults.

The incubation period is influenced by temperature but usually 7 – 14 days with the fry large enough to accept Artemia naupliimicroworm, etc., as soon as they become free-swimming.

NotesTop ↑

This species is a long-standing aquarium favourite and is produced on a commercial basis with wild fish very rare in the aquarium hobby outside the U.S.A.

A highly-deformed ‘balloon’ strain has been line-bred and is available on occasion.


  1. Goode, G. B., 1879 - Proceedings of the United States National Museum v. 2 (no. 73): 108-121
    A preliminary catalogue of the fishes of the St. John's River and the east coast of Florida, with descriptions of a new genus and three new species.

14 Responses to “Jordanella floridae – Florida Flagfish (Cyprinodon floridae)”

  • Joshaeus

    I can’t say I agree with this. While it is true that flagfish can spawn in typical killifish fashion, it will definitely guard its eggs in pits in some environments. It is believed to have to do with water depth – shallow water is more likely to cause the male to put on his best sunfish impression. This is a (rather blury) video of a flagfish guarding its spawn: https://www.youtube.com/watch?v=9yOZR29HtcQ

    Another video in a natural environment: https://www.youtube.com/watch?v=X_bwyVJD9P4

  • I’d say the fish in the video is a reproductively-active, and therefore territorial, male but it doesn’t appear to be protecting eggs.

  • Crackerjim

    Mine definitely not only defend the nest, but also fan the nest for several days after spawning. They are aggressive little fellas while seeing after the nest, usually for between seven and ten days. It’s very obviously not about the territory, ALL about the nest with my guys.

  • Hi Crackerjim. As stated in the profile, this species does not construct nor defend a nest and does not guard its eggs. Perhaps what you are seeing is territorial males?

  • Crackerjim

    Matt, all I can say is what I see – my males definitely do guard the nest and also stand on end to fan the eggs about a dozen times per hour. If an egg falls off of the Marimo ball that they seem to love to nest on, he will pick it up very gently and return it to the ball. Could be that my fish are not acting in the accepted way, but they are doing exactly what I’m relating. If I must, I’ll film it and post it on Youtube the next time they spawn, but it’d be sweet of ya to just take my word for it. While not college educated, I did take advanced biology in highschool, plus I worked at Woods Hole’s Sealab as an intern through highschool – I know observation and I know fish behavior, I’m not some amateur. Don’t mistake my tone – I’m smiling through this because, evidently I’ve got something special going on in my tank – that’s why I came to this forum – because the books I’ve read don’t mention these behaviors, and I wanted to let it be known that it’s not only possible, but it’s actually happening. My problem is that my females dart in and rob eggs and will eat the babies when they hatch. Going to set up a spawning tank and remove the adults about 7 days after the spawn, give the fry a chance.As for territorial behaviors, they do guard their own little piece of turf – but nothing like when they are guarding a clutch of eggs – with eggs, they are incredibly violent, will tear fins and knock off scales – without, it’s just a nudge or a bump – very pronounced difference. Remember – just because you read it in a book, that doesn’t make it the end-all / be all – scientific “facts” change every day to accommodate new data!

  • Crackerjim

    Also – the bright colors seen in the picture to the right are for regular territorial behavior – mine go really dark-colored when on a clutch of eggs and stay that color for the two weeks, or so that it takes to hatch them.

  • Michael

    Here is a link to an article in which the author describes two different spawning strategies that he has observed: http://aquafind.com/articles/jordan.php Depending on the depth of the tank, the fish spawned in both ways described here.

    My own fish have not yet spawned. They are in a shallow tank that should promote the nest guarding behavior by the male that some have reported.

  • Crackerjim

    Great article, Michael! Should likely replace the one quoted above since it is far more observant, taking in more parameters. The tank I’m writing of is a 25 gallon high – my fish are in fairly hard water, temps at 79/80 and the depth is at 16″ over substrate of 4 1/2″. Tank is planted with Java fern, several types of sword, anubius coffeefolia, moneywort, and a few others. I have two dominant males, each has his little “bower”. They do not “nest”, but have really loved the bowers that I constructed of vegetation and a 2 1/2″ Marimo ball for each. They prefer to spawn directly on the mossball, but usually deposit a few eggs in the Java fern, as well.

    Can someone tell me of a good source for proper moss / algae for these fish? I haven’t any. Their diet has been flake and frozen bloodworms. They do nibble at my plants, but not enough to surpass plant growth. Had considered a trip to a farm pond nearby, but don’t really want to risk parasites.

  • Crackerjim, your posts are not consistent. Earlier you were adamant that your fish formed nests with the males performing cichlid-like brood care behaviour, but now it appears this is not the case…

    It seems the facts have been somewhat overlooked regarding this species. For example, the article linked by Michael states it to be a specialised algae eater, yet this is not the case in any other member of the family Cyprinodontidae (currently 140+ species on at least 5 continents), plus its mouth shape is not that of a typical herbivorous fish. Similarly, no species in this family is known to practice broodcare, with all exhibiting a fairly comparable strategy whereby the eggs are deposited among vegetation or algae, most often within temporary territories established by males.

    In addition, there continues to be a total lack of photographic or video evidence that this species practices brood care. Males are territorial during the reproductive season, so perhaps in a confined space such as an aquarium this may be confused with egg guarding behaviour since they have nowhere else to go?

    Michael, it would be great to read of your experiences as your fish grow and hopefully breed.

  • Michael

    That is the plan!

    Re diet, my fish do eat algae, but not to the extent claimed by some sources. They also like blanched zucchini, and will chew up Hygrophila polysperma but no other plant species I have put in their tank. They eat flakes readily, and really love frozen brine shrimp and blood worms.

  • ThomasBontes

    There is a lot of very serious stuff published on this subject.
    Here is what a friend obtained from a good website specializated on Killifish.

    (sorry for my English)

    Saint Mary, C.M., C.G. Noureddine & K. Lindstrom. 2001. Environmental Effects on Male reproductive Success and parental care in the Florida Flagfish Jordanella floridae. {Ethology, 107 (11): 1035-1052.}
    Saint Mary, C.M., E. Gordon & R.E. Hale. 2004. Environmental Effects on Egg Development and Hatching Success in Jordanella floridae, a Species with parental Care. {J. Fish Biol., 65: 760-768, 2 figs.}
    Klug, H. & C.M. Saint Mary. 2005. Reproductive Fitness Consequences of filial Cannibalism in the flagfish, Jordanella floridae. {Animal Behaviour, 70 (3): 685-691, figs.}
    Klug, H., A. Chin & C.M. Saint Mary. 2005. The net Effects of Guarding on Egg Survivorship in the flagfish, Jordanella floridae. {Animal Behaviour, 69 (3): 661-668.}

    And many encouragements for seriouslyfish


  • Michael

    Reviewing the abstracts of these articles, and others on related topics from a Google search, it seems that biologists are quite convinced that male flagfish do exhibit parental care. They also speculate that parental care has recently evolved in this species.

    Thomas, thanks for the references.

  • JohnMorales

    Perhaps one source of confusion about how much parental care the male provides is due to there being two types of males.

    I forget what the proper term is, but clearly there is a smaller cuckolding male that lives on the fringes and breeds behind the back of the more typical large, brightly colored male that typically defends a territory.

    This little male is barely identifiable as a male based on coloration, and is barely 1/3rd the size of the normal sized male and female flag fish.

    He came along with the others in a batch of fish I ordered. At the time he wasn’t that much smaller than the others. Over time however while they more than tripled their size, he hasn’t grown at all.

    Now he is so much smaller than the others it’s pretty difficult to recognize him as one of them, especially since he does not congregate with the others when they decide to parley LOL

    I thought for a while that maybe I received a similar looking dwarf species.

    Then recently by sheer chance I caught him in the act of spawning with a much larger female flagfish in the classic surreptitious way sneak spawner males breed without the use of established territories.

    While the large boss male was elsewhere in his territory with several females, he took advantage of a female who decided to lay eggs while the territorial male’s attention were focused on the other females.

    Each time she nestled down a bit in to the algae to drop a few eggs, he pushed up against and slightly below her apparently to fertilize her eggs.

    This happened several times, and came to an abrupt end when the territorial male returned to the center of the territory, causing the tiny male to dart off to the fringes.

  • Michael

    Interesting, similar behavior occurs in several species of North American sunfish. I have read such males described as “cryptic” males.

Leave a Reply

You must be logged in to post a comment.