Florida Flagfish Care Guide: Tank Size, Diet, Algae-Eating & Tank Mates (Jordanella floridae)

The complete Florida Flagfish care guide from the team at Tropical Treasures Wyo — Cheyenne, Wyoming's freshwater specialty store. Florida Flagfish (Jordanella floridae) are one of the most colorful, hardy, and algae-eating native North American fish you can keep. This guide covers everything you need to set up, feed, and breed them successfully.

Quick Care Sheet — Florida Flagfish at a Glance

• Scientific name: Jordanella floridae
• Common name: Florida Flagfish, American Flagfish (American Flag)
• Origin: Florida and southeastern United States — native to swamps, marshes, backwaters, canals and ditches, and slow-moving rivers
• Adult size: 2–2.5 inches
• Lifespan: 2–3 years
• Minimum tank size: 20 gallons
• Temperament: Semi-aggressive, especially males during breeding
• Diet: Omnivore, strongly herbivorous — algae and plant matter are essential, with occasional insect larvae and micropredator feeding on small live foods like daphnia and live vinegar eels
• Temperature: 65–82°F (excellent for cool, unheated tanks)
• pH: 6.5–8.0
• Hardness: GH 5–20 (tolerant of hard water and lightly brackish water)
• Care level: Beginner-friendly

Looking to add some to your tank? Browse our live Florida Flagfish (Jordanella floridae) stock.

Natural Habitat & Background

Florida Flagfish are one of the few native US species that have become popular in the aquarium trade, thanks to their striking patriotic colors and famously voracious appetite for algae—including the dreaded "black beard algae" (BBA) that plagues planted tanks. In the wild, they inhabit shallow, heavily-vegetated freshwater marshes, backwaters, canals and ditches, and slow-moving streams across Florida, including habitats in the St. Johns River basin, their type locality. They tolerate huge temperature swings, varying salinity including lightly brackish water, and water chemistry that ranges from soft and acidic to moderately hard and alkaline.

That hardiness translates directly into the aquarium: Florida Flagfish are nearly bulletproof for beginners, do not require a heater in most North American homes, and can be one of the most cost-effective ways to control nuisance algae in a planted tank.

Florida Flagfish Appearance

Males

Adult males show vivid alternating bars of red, blue, and gold along the flanks—resembling an abstract version of the US flag (hence “American Flagfish”). Their dorsal and anal fins are tipped in red and edged with electric blue. Mature males display intensely during breeding and territorial standoffs, clearly showing their dorsal fin to assert dominance.

Females

Females are smaller and more subtly colored in olive and bronze tones, with a single dark spot near the rear of the dorsal fin. They lack the vibrant banding of males but glow softly under good lighting, blending well in marsh and backwater environments.

Juveniles

Juveniles resemble washed-out females until 4–6 months of age, when male coloration begins to develop as they mature.

Tank Size & Aquascape

Minimum Tank Size

A single pair of Florida Flagfish can live happily in 20 gallons. For a small group (1 male, 2–3 females), aim for 29+ gallons. Multiple males require 40+ gallons with heavy plant cover to break sightlines and reduce aggression.

Substrate

Sand or fine gravel works equally well. Flagfish like to graze on substrate-grown algae and biofilm, so a darker substrate also intensifies their colors.

Plants

Flagfish are happiest in heavily planted tanks. Dense vegetation:

• Breaks up territory and reduces male-on-male aggression.
• Provides spawning sites — they love depositing eggs in fine-leaved plants.
• Grows the algae and biofilm they prefer to eat.

Great plant choices include Jungle Vallisneria, Amazon Sword, Hornwort, Water Sprite, and Java Moss. Flagfish may nibble soft new growth but generally leave established plants alone.

Hardscape & Cover

Add driftwood, smooth river stones, and a few caves. Indian almond leaves tannins also enhance their natural blackwater origins and bring out richer reds in males, mimicking their native marsh and swamp waters.

Filtration

A modest hang-on-back or sponge filter is fine. Flagfish prefer moderate flow—not strong currents—as they evolved in swamp environments.

Lighting

Moderate to bright lighting is excellent. Flagfish actually display their colors most vibrantly under bright planted-tank lighting.

Water Parameters

Florida Flagfish are remarkably forgiving and adaptable to a broad range of water conditions:

• Temperature: 65–82°F. Unheated room-temperature tanks are perfectly acceptable. Avoid sustained temps above 84°F.
  
• pH: 6.5–8.0
• GH: 5–20 (tolerant of hard water and lightly brackish conditions)
• KH: 2–10
• Ammonia/Nitrite: 0 ppm
• Nitrate: below 30 ppm

Treat new water with Seachem Prime on every change. Monitor parameters with the API Freshwater Master Test Kit.

Diet & Feeding — The Algae-Eating Champion

Their Plant-Heavy Diet

Florida Flagfish are one of the very few aquarium fish that genuinely and reliably eat black beard algae (BBA), hair algae, and other nuisance algae. They also consume biofilm, soft plant matter, and tiny invertebrates like daphnia and insect larvae. In planted tanks, they patrol leaves and driftwood like dedicated algae crews, helping keep tanks clean.

Daily Feeding

Even though they eat algae, you should still feed them. Offer:

• A high-quality vegetable-rich flake or pellet daily.
• Blanched zucchini, spinach, or peas 2–3 times a week.
• Occasional frozen spirulina brine shrimp or live vinegar eels for color and protein.
• Sinking pellets like Liquid Gardens Shrimp Complete as a varied protein/plant supplement.

Underfeeding for Algae Control

If you specifically want them to clean BBA, slightly underfeed them—offer one small meal every other day. Hungry flagfish do the most algae work and actively graze nuisance hair algae as micropredator feeders.

Behavior & Temperament

Flagfish are bold, active, and curious in a community tank. However:

• Males display vigorously and can become aggressive toward each other in tanks under 40 gallons.
• Males may chase females persistently during breeding cycles—keep at least 2 females per male to spread out his attention.
• Slow, long-finned fish like guppies, bettas, and angelfish are NOT good tank mates—flagfish may nip their dorsal and anal fins.
• They are largely peaceful toward similarly sized, fast-moving fish.

Best Tank Mates for Florida Flagfish

Great Choices

• Fast-moving danios, white cloud minnows, and rosy red minnows (thrive in similar cool temps).
• Hardy livebearers (in larger tanks).
• Otocinclus or small algae catfish (won't compete directly for algae but ignore the flagfish).
• Most Corydoras catfish—they occupy the bottom and avoid mid-water conflict.
• Small hardy barbs like cherry or rosy barbs.

Avoid

• Long-finned bettas, guppies, and angelfish (nip-prone).
• Slow-moving fish that can't escape sudden chasing.
• Very tiny shrimp—cherry shrimp juveniles will be eaten. Adult Amano shrimp can usually hold their own.
• Fish requiring tropical temps above 82°F long-term.

Breeding Florida Flagfish

Flagfish are substrate spawners and males are the rare aquarium-fish dads—they actively guard the eggs, exemplifying strong parental care. Breeding is straightforward in a dedicated tank.

Setup

A 10–20 gallon tank with fine-leaved plants like Java Moss, a sandy substrate, a sponge filter, and gentle flow. A DIY spawning mop also works exceptionally well.

Conditioning

Feed heavily with protein and vegetable foods for 1–2 weeks. Slightly drop the temperature, then raise it back to 75°F to simulate a seasonal warming cue.

Spawning

The male claims a small territory, builds a slight depression in the substrate, and entices females in. Females scatter eggs in plants or substrate, and the male fertilizes them as they're laid. He then guards the territory for the next 5–7 days until eggs hatch.

Raising Fry

After hatching, remove the male and let the fry develop on biofilm and infusoria. After a week, feed crushed flake, newly hatched brine shrimp, or commercial fry food.

Common Health Issues

Flagfish are exceptionally hardy, but watch for:

• Ich (Ichthyophthirius): White spots; treat with heat (slowly to 84°F) and standard ich medication. Read our hospital tank guide for advanced treatment setups.
• Fin nipping injuries from other males: Separate aggressive individuals; provide more plant cover.
• Bloating from overfeeding protein: Skip protein for 2–3 days and feed only blanched veggies.

Use API Stress Coat after any handling or transport.

Where to Buy Florida Flagfish

You can find live Florida Flagfish (Jordanella floridae) at Tropical Treasures Wyo, in-store in Cheyenne or shipped to your door. We typically stock a few juveniles plus a small number of breeding-age adults—ideal for starting an algae-control team or a small breeding setup.

FAQ — Florida Flagfish

Will Florida Flagfish really eat black beard algae?

Yes—they are one of the very few species that reliably consumes BBA, especially when slightly underfed. A pair can clear a moderately infested 20-gallon tank within 2–3 weeks.

Do Florida flagfish eat algae?

Absolutely. Florida Flagfish voraciously graze on black beard algae, hair algae, and other nuisance algae, as well as biofilm and plant matter, making them an excellent algae eater for planted tanks.

Are Florida Flagfish good community fish?

Yes, with some caveats. They are semi-aggressive, with males displaying and chasing tank mates during breeding, but are generally peaceful community members when housed with fast-moving or similarly sized fish.

Are flagfish peaceful?

They have a semi-aggressive temperament. Males can be territorial and chase each other, but overall they are peaceful toward non-aggressive, fast-moving community fish.

Do I need a heater for Florida Flagfish?

Not usually. They thrive at room temperature (65–78°F). Avoid heaters set above 80°F long-term.

Can I keep multiple males together?

Only in 40+ gallon tanks with heavy plant cover. In smaller tanks, the dominant male will harass others relentlessly.

Will Florida Flagfish eat my plants?

They may nibble tender new growth on soft stem plants but generally leave established plants intact. Hardy plants like vallisneria, Amazon swords, and Java Moss are perfectly safe.

How big do Florida Flagfish get?

2–2.5 inches as adults. Males slightly larger than females.

How long do they live?

2–3 years on average in well-maintained tanks.

Can I keep them with shrimp?

Adult Amano shrimp usually survive, but small Neocaridina shrimp (especially juveniles) will be hunted and eaten. Don't combine them if you want a shrimp colony.

What's the best diet for color?

Plant-heavy with weekly frozen spirulina brine shrimp. The natural carotenoids in algae and spirulina intensify reds in males.

How do I tell male from female Florida Flagfish?

Males show bold red/blue/gold banding. Females are smaller and olive-tan with a single dark spot near the back of the dorsal fin.

Visit Us in Cheyenne

Stop by Tropical Treasures Wyo to see live Florida Flagfish in action, get tank-specific advice, and pick up everything you need to set up a successful planted tank with native algae eaters. We carry plants, foods, water conditioners, and a rotating selection of compatible tank mates.

For more reading, see our Best Background Aquarium Plants, our Best Fish Food for Community Tanks guide, and our DIY Spawning Mop Tutorial.