Betta (Siamese Fighting Fish) Stocking
Minimum 5 gal · 2.5" adult · low bioload · aggressive.
Estimated bioload
75%
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Bioload-based: it weighs adult size and waste output, not the oversimplified "1 inch per gallon" rule.
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Keeping Betta (Siamese Fighting Fish)
The Betta (Siamese Fighting Fish) grows to about 2.5 inches and needs a minimum of 5 gallons. Its bioload is low, meaning it produces a small amount of waste for its size, a key factor the "one inch per gallon" rule ignores. It doesn't need a large group, but plan tankmates around its temperament. Temperament is aggressive, so choose tankmates carefully or keep it in a species-only setup. Use the calculator above to see how a group fits your tank's real volume before you buy.
Frequently asked questions
What size tank does a Betta (Siamese Fighting Fish) need?
At least 5 gallons. They can be kept without a large group, but check tankmate compatibility.
Is the Betta (Siamese Fighting Fish) peaceful?
Temperament is aggressive. Reaching about 2.5" as an adult with a low bioload, plan tankmates and filtration accordingly.
Keep going with the same pet
Not sure of your tank's exact gallons? Measure it with the aquarium volume calculator first.
Your dog's age in human years, breed-size adjusted, not the ×7 myth.
Your cat's age in human years using the real feline curve, not the ×7 myth.
How much to feed: daily calories and cups by weight, activity and life stage.
Tank gallons and liters from your dimensions: rectangle, cylinder, hex and more.