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American flagfish question

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May 9, 2023
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Perth, Australia
About American flagfish, is it okay to keep a pair of them in a 40cm cube (64L) tank? I am new to American flagfish, and I never kept them before. There are no plants native to Florida in Perth LFS's. So I have no choice but to put plants from different areas of the world.
I believe flagfish need at least 20 gallon long rectangular tank. A 29 gal would be even better. Bigger tank = more fish.
And @Fishmanic, let me tell you a story behind my love of flagfish. I first saw flagfish in a pond shop in Cockburn (coh-burn), Australia. The males were displaying their colours in an empty tank on top of other tanks. They cost $9 in the pond shop, but I wish I got some and prepped the tank for them, but couldn't due to some family stuff. I wanted to chat to you and @GaryE about the Florida native. I was thinking 'Oh, that would be a nice fish for a 64L 40cm cube tank. I might plan to do a project exclusively for them'. I now realise they must live in 20 gallons or more to thrive.

This fish is only found in Florida and they are common around the world in LFS's. This fish is a gem and although breeding them can be difficult, expert hobbyists have given it a shot once or twice. I am enthusiastic about flagfish due to them being a North American native, but since I don't usually see North American natives in Australia, it is the only American native killifish that is sold in LFS's here. I've been wanting to keep them a long time and I understand that you might not want to keep them, but it's a lovely fish to keep in tanks that are 54L or more.

Maybe I should keep a species-only tank for flagfish. In my opinion, they don't do well in community tanks. I wonder that if other LFS's sell other North American fish (shiners, minnows, etc.).
Fun fact - according to fishbase they hold the Guinness World Record for the fish with the fewest eggs... 20, spawned over several days. Hmmm, not sure of the validity of that. If GaryE comments maybe he can weigh in there...
I tried to keep them once many moons ago, in a small community tank. They were outright vicious to everything and had to be quickly removed. They’re never seen in the UK, mainly for that reason.
I’m sure their mother loves them though, and that if kept appropriately they can be a rewarding fish to keep.
I have one bigger one, & one smaller one ( different ages ) so I'm not sure if they are males or females??? but they are in a 55 gallon with no identity, a mix of fish, from rainbows to Sailfin Molly's to high fin sunset platy's... so far they are playing nicely in my tank... it may take some restraint not to nip on the sailfins or high fin platy's... they came in, from an average on line seller, not looking good, & I got an Ich outbreak, as I didn't have quarantine tanks running yet... they have recovered now, & the bigger one is a very pretty fish... I didn't realize they were an American Killi fish, when I got them
Here is an article I wrote back in 2009 that might be helpful. Since then, I have moved to Florida and can now observe these beautiful fish in their native habitat. Interesting note: the American-Flag Fish is hyphenated because the name is a compound adjective.

One of the joys of fishkeeping is showing another experienced aquarist your latest fish acquisition and hearing, "Whoa, beautiful fish, what is it?" This is my experience with the American-Flag Fish (Jordanella floridae). I am not an impulsive buyer and as with the other ornamentals kept in my fish room, I researched and planned for more than a year before special ordering six of these fish from my local pet shop. The reason for the long wait will be explained momentarily.

Jordanella floridaeare ray finned fish from the family Cyprinodontidae (killifishes, pupfishes and toothcarp) and are considered to be a single genus (Jordanella) of the North American pupfish. This beautiful native fish gets its name because of a striking resemblance to the Stars and Stripes. Determining the sex of the fish is simple. The male is brightly colored with red, horizontal stripes running from behind the gills to the leading edge of the caudal fin. This pattern is only interrupted by a dark, middle of body spot. The greenish-white scales twinkle like little stars and the head sports a distinct blue hue giving this fish a patriotic appearance. Most literature reports the female coloration is more subdued than the male. But careful examination indicates they too have the same colors as the male and in fact, two of my females sport coloration nearly as vivid as the males. The female is clearly identified by a dark spot on the trailing edge of the dorsal fin. Both sexes grow to about two and a half inches in length however the male body has more mass and is typically wider than the female.

Discussions with several fish farms revealed this is not a high demand species. It is my understanding most of the American-Flag Fish are captive bred in small ponds in Florida with the original stock usually collected from ditches and slow-moving streams. A very small quantity are aquarium bred and simply traded between hobbyists. A couple of experts speculated the low demand and frequency of wild sample replenishment perhaps explains the consistency of this fish's appearance. My fish look like clones of the samples photographed in the early 1900's. I have no reports of hybridization.

The American-Flag Fish was named after famous ichthyologist, David Star Jordan and the State of Florida. For years, this beautiful fish was curiously available to our fellow aquarists in Europe and virtually unknown here in the USA. There is much confusion concerning the distribution of this fish. After talking with more than ten biologists in the State of Florida and Alabama I learned this fish is ubiquitous in the backwaters and springs and estuaries below 29 degrees of latitude in the State of Florida. There are reports of this fish being collected in estuaries of Alabama, Mississippi and Louisiana but I have not been able to confirm the validity of these claims. Some literature reports the distribution of the American-Flag Fish as far west as the Yucatan peninsula. Other writings refer to the species found in the Yucatan as Jordanella pulchra. It is my opinion that these authors are actually referring to the Garmanella pulchra which like Jordanella floridae shares a mid-body black spot and at a quick glimpse, could easily be mistaken for Jordanella floridae. The American-Flag Fish is primarily a freshwater species but is also reported to sometimes be found in brackish waters. One fish farm owner indicated they are sometimes found in minimally brackish water (probably not exceeding SG1.004) and speculated the fish more than likely ended up flowing down stream into an estuary after a hard rain. It is difficult to determine the salt tolerance of this fish since simply dipping a hydrometer into an estuary where they are found will not produce credible results. Because of estuarine circulation, freshwater entering an estuary will tend to flow along the bottom under the salt water. It makes me wonder, if these fish are dip netted from an estuary, are they pulled from primarily fresh water or brackish water? Do they live long-term and breed in brackish water, temporarily traverse from freshwater to brackish water seeking nourishment or are they simply "castaways" that were just washed out to sea? Discussions with fish farmers who propagate Jordanella floridae revealed these fish are extremely tolerant and adaptable to a variety wide of water conditions ranging from soft to extremely hard and endure an array of pH values.

Unfortunately, being small killifish, American-Flag Fish are often touted as an aggressive species. Nothing could be further from the truth. Some of the "hard facts" promulgated about this fish seem to be nothing more than urban legend. They really won't eat every plant in your tank, nor will they group attack and kill an algae eater. Years ago, adding insult to injury, this fish was often misidentified as a small sunfish or classified as a cichlid. These very peaceful fish are perfect for a species tank but with careful planning can be an excellent choice for a community tank if given proper conditions and suitable tank mates. Fish breeders often use Jordanella floridae in their Koi rearing ponds for algae control which is an excellent example of the American-Flag Fishes geniality.

The long-term planning: A common thread of accounts from those who have actually kept the American-Flag fish is its attraction to thread algae. In fact, some aquarists obtain this fish solely to rid their aquarium of thread algae outbreaks. This is unfortunate. It is much like a hobbyist purchasing a bunch of freshwater mussels to clear turbid water. In both cases, the fish and mussels do such a thorough job that they can actually starve if not provided with additional nourishment. Knowing this species primarily thrives on a diet of fresh string algae, I chose to obtain my fish in the springtime. Normally, I take precautions to avoid uncontrolled algae blooms in my outdoor ponds. But this year, in order to ensure a continuous supply of string algae, I encouraged growth in anticipation of the arrival of my American-Flag Fish. It was very disconcerting at first because the algae overtook one pond, and it was difficult to restrain myself from taking action to eliminate it! Another long-term project was initiated nine months prior to the arrival of my fish. I placed a large driftwood log into one of my indoor ponds, directly under a blindingly bright reptile light in order to achieve a thick carpet of algae growth. I anticipated the algae carpet would be a backup source of fresh food for the American-Flag Fish in the event the hair algae source from my garden pond became depleted.

I decided to create a backwater themed aquarium using a well-seasoned, 29-gallon tank. The substrate is a combination of sand and 2-3mm size quarts gravel. The depth of the substrate varies from two to four inches. Three large driftwood logs provide an interesting wetland effect. The tank is moderately planted with an Amazon Swords, Giant Hairgrass, Java Fern, dwarf Vallisneria, Red Wendth, Water Sprite and Hornwort. Filtration consists of one sponge filter and a hang-on-the back filter. An ideal temperature range is between 65 and 75 degrees Fahrenheit. Lighting is provided by a full-spectrum strip. I made a fish "feeding troth" using a plastic aquatic plant container and a two-inch rock. One end of the string algae is placed inside the container and the rock secures it in place. The fish feeder is a convenient way to anchor the hair algae harvested from the pond and keeps it from free-floating and becoming entrapped and clogging the filter uptake tubes.

I special ordered my American-Flag Fish from a locally owned pet shop. The six juveniles (2-males, 4-females) were really only identifiable as Jordanella floridae by their mid-body black spots.

Following introduction into the 29-gallon tank, the fish hid behind a log for about 30minutes. Then something interesting happened. One male ventured out and started attacking the 6-inch long by 2-inch wide by 2-inch-thick clump of string algae which was slowly waving in the gentle current. The remaining five eventually emerged and I witnessed what seemed like a Hollywood movie feeding frenzy. It was simply unbelievable. The entire mass of string algae was completely eaten in two days. So much for my concerns about an overabundance of string algae in my outdoor pond! Throughout the summer they have eaten all of the original pond grown string algae which probably weighed several pounds and a new growth of string algae that I hurriedly propagated barely supporting their needs. Jordanella floridae are omnivorous and supplemental food consists primarily of newly hatched brine shrimp and live daphnia and sometimes frozen foods such as blood worms and mosquito larvae. Their food preference is clearly string algae closely followed by live daphnia. They are also occasionally fed flake food which they accept. The fish constantly forage at all levels of the aquarium. Incidentally, the algae carpeted log is almost completely cleaned of any growth with the fish incessantly pecking away at the "greenery." None of the plants have been disturbed by the fish. I had some concern they might eat the Hornwort with its soft, flowing fronds but they show no interest in any of the plants.

Breeding Jordanella floridae is quite easy. I conducted 25%partial water changes twice weekly and noticed courtship followed by breeding soon thereafter. One pair mated with the male pushing against the female producing what looked like 5 eggs that were laid near the water's surface in a clump of Water Sprite. Unfortunately, they spawned near the string algae feeding troth. This was a stroke of bad luck for the other fish because the male guarding the nest promptly chased the other fish away from their food source. The male is quite vigilant in safeguarding the nest and perhaps this is where the reputation of cichlid-like aggression originated. Relocation of the string algae resolved the feeding problem. Typically, eggs hatch at nearly the same time but that is not the case with this fish where eggs can hatch over a period of a couple of days. I am not sure if this is due to water temperature or if it is just a characteristic of this unique fish. The fry tend to hang out near the surface and really should be removed to a shallow grow out tank. Initially feed them very small organisms such as infusoria and as they grow, transition to newly hatched brine shrimp. Aside from the tendency to conscientiously protect their nest, the American-Flag Fish is a very peaceful schooling fish. Some published reports recommend keeping only males together. I have been very successful with mixed sexes in the same tank. Given a moderately planted, spacious aquarium and plenty of fresh food these fish will coexist nicely and proudly display their patriotic colors.

Five Suitable tank mates for adult American-Flag Fish
  1. Zebrafish
  2. Angelfish
  3. White Cloud Mountain Minnows
  4. Goldfish
  5. Corydoras
How to grow hair algae
Deliberately propagating hair algae probably seems counterintuitive. But there are times when we need hair algae to feed specialized species such as the American-Flag Fish. Hair algae is the product of excessive nutrients and light. An opaque 2x2 foot square plastic container purchased from a discount store is ideal. This is a warm weather project so place the container outside. Do a partial water change from an aquarium and pour it into the plastic container. It is easier to get started by taking about 6-inches of hair algae and placing it into a fishless container. Stir in a cup full of old fish food and place the container where it will receive direct sunlight for about 4 hours and indirect light for at least 8 hours. Every time you do a partial water change in your aquarium, dump the water into your hair algae container. The combination of high nitrates, warm, stagnant water and bright lighting will ignite a explosion of hair algae.

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