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American Flagfish Care Guide


If you are struggling with hair algae or black beard algae, the American flagfish might just be the exact fish you are looking for.

With it’s interesting brilliant coloration and striping, it’s no wonder where the American flagfish got their name.

Originating from slow moving waters, marshes, swamps, lakes, and ponds from Florida to the Yucatan Peninsula, these small brightly colored fish can make a stunning addition to an aquarium.

Flagfish only get to be about 2 inches in size and on average live 3 years, but some have been recorded to live as long as 8 years in the right conditions.

Tank Set Up

When it comes to tank set up, keep in mind that flagfish do best in well-established aquariums, so you want to make sure the tank is fully cycled, and the water parameters are stable before adding them to the aquarium.

The minimum tank size required to comfortably house a pair of the American flagfish is 20 gallons, however if keeping a larger group 30 gallons or larger is recommended.

They do best in soft, neutral to slightly acidic water with a pH of between 6.5-8 and temperatures between 64°-86° with a KH of 2-19 dKH.

Flagfish really thrive in a well planted aquarium. Driftwood, floating plants, and a darker substrate are great if you are trying to recreate their natural environment.

When choosing a filter for your flagfish, you will want to choose low flow filtration. Sponge filters are a great choice, but if you do have a hang on back filter you could always add a baffle to help slow the flow for your fish.

Tank Mates

When it comes to tank mates, keep in mind that flagfish, especially male flagfish, can get aggressive, and may nip and the fins of slower moving fish, so you will want to avoid keeping them with slower fish with long fins.

These fish tend to do best with more active tank mates such as neon, rummy nose, or cardinal tetras.


When it comes to diet, flagfish are far from picky eaters. These fish do well with a diet consisting of a high-quality pellet food, along with frozen or live foods such as bloodworms, tubifex worms, and brine shrimp. Also, if there is not enough algae present in your aquarium, you may need to give them blanched vegetables such as cucumber, spinach, or kale, or you can supplement with algae tablets.


When it comes to breeding, the American flagfish is relatively easy to breed, even for beginners. They are a fractional spawner, with females depositing eggs on a pretty continuous basis, if kept in warmer temperatures.

If they are normally kept in a community aquarium, you may want to set up a separate breeding tank with plenty of plants or cover for the once hatched fry to feel safe in, and because males can be very aggressive towards one another, only keeping 1 male in your tank is strongly recommended.

When choosing your mating fish, adult males have a more extended dorsal and anal fin and are far more brightly colored than their female counterparts. Females also tend to have more rounded bellies and have a dark blotch on the posterior portion of their dorsal fins that males do not have.

While the flagfish is not known to aggressively eat their young, it is still common to remove the parents from the breeding tank, or to place the eggs in another well planted tank to hatch and grow.

Once fry have hatched and are free swimming, which typically takes between 7-10 days, you can then feed green water/infusoria and as the fry grow you can start feeding baby brine shrimp until they are large enough for other foods.

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