Recommended Aquarium Tank Size for Betta Fish

All bettas have a labyrinth organ, a lunglike adaptation that enables the fish to breathe air. Because of this, Siamese fighting fish can survive in unusually small, polluted tanks. While the betta's resilience makes it a popular fish for small tanks, experts disagree about the minimum tank size necessary for keeping these hardy freshwater beauties.

  1. Potential Sizes

    • Experts offer widely differing recommendations regarding the size of tank for an adult betta. While the pet supply center Petco recommends fish bowls as small as one liter, some aquarists believe that an adult male betta can thrive in nothing less than a 10-gallon aquarium.

    Misconceptions

    • Because of the labyrinth organ adaptation, bettas can survive in bowls and small tanks for surprisingly long periods of time; this has led to the common misconception that bettas thrive in cramped environments. In reality, bettas benefit from the open space and stable water chemistry provided by a larger aquarium.

    Considerations

    • A betta's ability to thrive in a small tank may depend on many factors. Small, docile female bettas may be able to thrive in a tank as small as one to two gallons; however, large, mature, active males may need a minimum of five.

    Maintenance

    • Small tanks may appear to be lower-maintenance than their larger counterparts; however, they require frequent water changes and close monitoring of water parameters. Larger tanks tend to have more stable water chemistry because nitrate pollution is diluted throughout the aquarium. As a result, they require less labor input than small tanks.

    Tank Mates

    • The minimum tank size for a betta depends on the presence of tank mates. Aquarists who intend to keep more than one male betta should use an aquarium containing at least 55 gallons of water. A 20-gallon minimum is recommended for more than one female betta. Several bettas may be kept together in a relatively small aquarium only if secure dividers prevent them from fighting.

    Effects of Small Tanks

    • While some bettas can survive in small, unfiltered tanks, they tend to be less attractive and less healthy than those kept in larger tanks. Bettas kept in small tanks and bowls tend to be more prone to disease because of chronic nitrate poisoning and ammonia buildup. They may have pale coloration and shorter fins, and many engage in self-destructive behaviors such as nipping their own fins or ramming against glass.