April 8, 2016 PetGuide
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  • Group: Freshwater
  • Size: Small
  • Temperament: Semi-Aggressive
  • Aquarium Size: Small
  • Swimming Region(s): Mid-Range
  • Suitable Tank Mates: Minnows, Characins, Fast-Swimming Fish, Narrow-Bodied Fish
  • Difficulty Of Care: Weekly

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Flagfish are a small fish that are semi-aggressive in nature. These fish may not do well if multiple males of the same species are kept together, especially in a small tank.

Flagfish are a small fish that are semi-aggressive in nature.

The Flagfish is a type of pupfish that is native to Florida. Pupfish are a group of small ray-finned fishes related to killifish which are primarily found in North America.

The coloration of varies slightly from one species to another, though some species are very colorful. The American Flagfish, for example, has iridescent blue-green scales with alternating stripes of red and blue running horizontally along the body.

The Flagfish tends to inhabit shallow, slow-moving waters that are densely planted. These fish can sometimes be found in swamps, backwaters, and marshes and they have even been found in brackish waters. These fish prefer a temperature range between 66°F and 72°F with a pH between 6.7 and 8.2 and a water hardness between 6 and 20 KH. They should be kept in densely planted tanks with driftwood and rocks for decoration and dark substrate to bring out their coloration.

These fish tend to inhabit shallow, slow-moving waters that are densely planted.

This is a mid-range fish for the most part, though it will sometimes feed on decaying plant matter and algae in the aquarium. These fish will eat just about anything, including flake foods and pellets as well as live, frozen, and freeze-dried foods. Feeding these fish a rich diet of high-quality foods will help to bring out its natural coloration.

Also read: Setting a Schedule for Routine Tank Maintenance

Flagfish are egg layers and they are generally not difficult to spawn in the home aquarium. Females of the species are larger and more full-bodied than males, plus they have a little more yellow in their coloration. During spawning, eggs are generally released individually or in small batches on various surfaces including plants and tank decorations.

American Flagfish (Jordanella floridae)

Photo credit: Karel Zahradka/Shutterstock; boban_nz/Shutterstock

Other Fish

Go to Piranha


  • Group: Freshwater
  • Size: Medium to large
  • Temperament: Aggressive
  • Aquarium Size: Large (50+ gal)
  • Swimming Region(s): Middle
  • Suitable Tank Mates: Tetras, Guppies, Other piranhas of the same species
  • Difficulty Of Care: Daily care – suited for the experienced aquarist
Go to Tigerfish


  • Group: Freshwater
  • Size: Large, Extra-Large
  • Temperament: Semi-Aggressive
  • Aquarium Size: Large
  • Swimming Region(s): Mid-Range
  • Suitable Tank Mates: Other Fish of Similar Size; May Sometimes Be Kept in Groups with Own Species
  • Difficulty Of Care: Weekly