Florida Flag Fish: From Care to Compatibility

The Florida Flag Fish, scientifically known as Jordanella floridae, is a small, vibrantly colored fish native to Florida’s springs, rivers, and swamps. The Flag Fish makes a stunning addition to coldwater aquariums with males displaying bright red and blue horizontal stripes and females a more understated yellow and olive coloration.

While peaceful community fish are often preferable for home aquariums, the Flag Fish is known to be mildly aggressive and territorial, especially during spawning. However, they can thrive in a diverse community environment with proper tank setup and selection of compatible tank mates.

This comprehensive care guide will cover everything you need to know about the Florida Flag Fish, from diet and tank requirements to breeding and behavior. You’ll also find tips on which fish make the best tank mates and curbing aggression. By understanding the needs of this species, you can create a thriving underwater community.

Overview of the Florida Flag Fish

The Florida Flag Fish is a small, colorful fish in the Cyprinodontidae family, native to various bodies of water in Florida. Here are some key facts about this fish:

  • Scientific Name: Jordanella floridae
  • Max Size: Up to 2.5 inches
  • Lifespan: 5 years in captivity
  • Care Level: Easy to Moderate
  • Temperature Range: 64-72°F
  • pH Range: 6.7-8.2
  • Diet: Omnivorous
  • Origin: Springs, swamps and rivers in Florida

In the wild, Flag Fish inhabit vegetated areas in slow moving springs, rivers, ponds and swamps. They tend to school together, especially during spawning periods. Males are vividly colored with horizontal blue and red striping while females are more subdued with olive green and yellow coloration.

While mostly peaceful, Flag Fish can be aggressive toward one another, especially males competing for territory and mates. Providing ample space and hiding spots can allow them to establish individual territories. Their vibrant colors and active nature make them an appealing choice for community aquariums when properly cared for.

Diet and Feeding

In the wild, the Florida Flag Fish is an opportunistic omnivore that will consume a variety of foods including:

  • Algae
  • Aquatic plants
  • Small insects
  • Crustaceans
  • Larvae
  • Zooplankton

This varied diet should be replicated in captivity. Here are some dietary guidelines:

  • High quality flakes with spirulina or algae to replicate plant matter
  • Algae wafers or tablets to graze on
  • Occasional treats of frozen or live foods like brine shrimp, bloodworms or daphnia to provide animal protein
  • Blanched vegetables like zucchini or spinach
  • Supplements with algae or spirulina

Feed a high quality flake as the staple diet 1-2 times daily. Offer algae wafers or vegetable matter several times a week. Live or frozen foods should comprise no more than 20% of total diet as an occasional treat.

Flag Fish are active and should be fed accordingly. Make adjustments based on appetite and body condition. Uneaten food should be removed promptly to avoid fouling the water.

Aquarium Setup and Care

To thrive, Florida Flag Fish require the following aquarium conditions:

Tank Size

  • Minimum 10 gallons for small group
  • Larger tank preferred, 30+ gallons for community

Water Parameters

  • Temperature: 64-72°F
  • pH: 6.7-8.2
  • Hardness: Soft to moderately hard water


  • Canisters or hang-on-back filters adequate
  • Ensure minimal water flow in tank


  • Fine gravel or sand substrate
  • Driftwood, rock caves and aquatic plants
  • Floating plants like hornwort appreciated
  • Provide plenty of sight barriers


  • Weekly 25% water changes
  • Test water parameters routinely
  • Clean filter media as needed

Given their small size, a 10 gallon aquarium can house a small group of 6 or less Flag Fish. However, a larger tank is always preferable to provide ample territory and minimize aggression. A heavily planted tank with rock caves and driftwood offers sight barriers and places to evade more aggressive fish. Keep water parameters stable and perform routine maintenance.

Algae Consumption

One of the benefits of the Florida Flag Fish is their propensity to consume algae in the home aquarium. They are eager grazers on most types of algae including:

  • Green algae
  • Brown algae
  • Blue-green algae
  • Black beard algae
  • Hair algae

They can be effective cleaners of tanks with persistent algae problems. However, their algae consumption should be supplemented with other foods as described above to ensure a balanced diet. Relying solely on naturally growing algae is not enough to sustain them.

Provide algae wafers, spirulina flakes and blanched veggies to satisfy their herbivorous tendencies. Consider adding them to tanks where you are battling stubborn algae growth to help control it naturally. Just be sure to address the underlying cause of the algae as well.

Availability and Pricing

The Florida Flag Fish is bred prolifically in fish farms in Florida and sold throughout the United States. You may be able to find them at:

  • Local fish stores
  • Pet store chains
  • Online retailers

Pricing can range from $3-$10 depending on size:

  • Juveniles: $3-$5
  • Young adults: $5-$8
  • Full grown adults: $8-$10

Inspect fish carefully for signs of disease and only buy from reputable sources. Quarantine new arrivals for 2-4 weeks to prevent introducing disease. Florida Flag Fish are very hardy when acclimated slowly to new tank parameters.

Size and Life Span

In the wild, Flag Fish can reach 3 inches in length but average around 2 inches in home aquariums. Other key facts about their size and life span:

  • Max Size: 2.5 inches
  • Maturity: 4-6 months
  • Life Span: 3-5 years with proper care

Males tend to be smaller, reaching only 1.5 – 2 inches compared to females, often larger. Provide a nutritious diet with variety and optimal water conditions to maximize growth and life span.

Tank Mates and Compatibility

Florida Flag Fish are largely peaceful toward tank mates, but caution is still required when choosing appropriate community members. Some guidelines include:

Good Tank Mates

  • Small peaceful schooling fish like neon tetras, white clouds or harlequin rasboras
  • Bottom dwellers like pygmy corydoras, kuhli loaches or otocinclus
  • Dwarf crayfish or Amano shrimp (may prey on small shrimp)
  • Snails like nerites

Questionable Tank Mates

  • Male guppies, bettas, or fancy guppies – long flowing fins may be targeted
  • Angelfish or other large slow moving fish
  • Ornate small fish like peacock gobies that may draw aggression
  • Shrimp or snails that can fit in their mouths

Avoid Tank Mates

  • Aggressive fish like tiger barbs that may fin nip or bully
  • Cichlids that compete for territory
  • Nippy fish like danios that are too active
  • High fin mollies, angel fish or bettas whose fins may be nipped

The keys to selecting compatible tank mates are choosing fast moving schooling fish that occupy the upper levels of the tank. Bottom dwellers are ideal tank mates as they share different zones. Avoid long-finned, slow moving species.

Keep tank mates of similar size and temperament. Monitor for aggression or harassment and have a backup plan to isolate bullies if issues arise. Never add Flag Fish to established tanks as this can trigger territorial disputes.

Aggressive Behaviors

While mostly peaceful toward tank inhabitants, male Flag Fish can exhibit aggressive behaviors toward each other, especially when competing for territory or defending spawning sites.

Some signs of aggression to watch for include:

  • Nipping or shredding fins of other males
  • Intense chasing, especially during spawning periods
  • Flaring gill covers and posturing when facing off
  • Continually disrupting spawning pairs
  • Dominating prime habitats leaving others no shelter

There are several techniques you can implement to limit male Flag Fish aggression:

  • Add more plants, rock caves and driftwood to break up sight lines and create more territories
  • Rearrange decor and plants during weekly water changes to disrupt territories
  • Increase tank size to over 30 gallons to provide more swim space
  • Maintain a larger group of 6 or more individuals to spread aggression
  • Use tank dividers to separate relentless bullies if needed
  • Remove aggressive males as a last resort to protect other fish

While some conflict is normal, especially during spawning periods, male Flag Fish may need added measures to curb relentless harassment of tank mates or competitors. Be prepared with backup tanks and plans if aggressive issues persist.

Breeding the Florida Flag Fish

While challenging, Florida Flag Fish can be bred in home aquariums with optimal spawning conditions. Here’s a quick overview:

  • Use at least a 10 gallon breeding tank densely planted with fine leaved plants
  • Floating plants like duckweed or java moss are ideal spawning sites
  • Maintain slightly warmer temps of 72-74°F to trigger spawning
  • Condition breeders with high protein live foods like brine shrimp
  • Lower pH slightly to 6.5-7.0 and use peat filtered water
  • Provide spawning mops, marbles or plant leaves for egg deposition sites

The male will entice the female beneath spawning sites where she will deposit adhesive eggs individually. He will follow to fertilize them. The parents may need to be removed after spawning as they will readily consume the eggs.

The eggs will darken within a day and hatch approximately 48 hours later. The tiny fry can be fed infusoria, finely crushed flakes or powdered fry foods. Rear surviving fry to adulthood to continue breeding this striking Florida native.

Comparison to Similar Species

The Florida Flag Fish resembles other killifish species inhabiting North America. Here’s a quick comparison to similar species:

Bluefin Killifish

  • More blue sheen on body and fins
  • Lack distinct red horizontal stripes
  • Found along Atlantic coastal plains

Rainwater Killifish

  • Dark vertical bars on body and fins
  • Red on fins and upper tail only
  • Found in ditches and swamps in southeast

Golden Topminnow

  • Metallic yellow sheen on body scales
  • Black rounded spots rather than stripes
  • Very tolerant of wide range of habitats

While similar in body shape and fin placement, the color patterns of the male Flag Fish stand out from other killies. The vibrant horizontal red and blue striping is distinctive. Examine the markings, fin shapes and coloration to identify properly.

Should You Keep the Florida Flag Fish?

The Florida Flag Fish is a colorful, active fish that can make a striking addition to peaceful community aquariums. While male aggression can be an issue, there are ways to curb territorial behaviors through proper tank setup and management. Their ability to help control nuisance algae makes them excellent cleanup crew members.

Here are some pros and cons to consider when deciding if the Flag Fish is suitable for your aquarium:


  • Bright coloration, especially vibrant males
  • Helps consume unsightly algae in tank
  • Peaceful toward most tank mates if given space
  • Active swimmers that use all areas of tank


  • Males can be aggressive toward each other
  • May nip fins of slow moving tank mates
  • Require lower temperature range than most tropical fish
  • Breeding can be challenging

Provided with an adequately sized tank and appropriate tank mates, a small group of Florida Flag Fish can add splashes of color and activity to coldwater community aquariums. Their energetic behaviors and algae grazing habits make them interesting to keep.


The Florida Flag Fish, a vibrant fish native to Florida, can be a great addition to community aquariums. They thrive in tanks with plants and sight barriers, and their propensity to consume algae makes them excellent cleanup crew members. Consider adding a small group to a coldwater community tank to maintain their vibrant nature. However, research their needs and plan for potential aggressive issues between males. With proper care, the Florida Flag Fish can bring a bit of their native Florida waters into your home.