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SESK: Stuff Everyone Should Know · sesk.info/fish-tank-water-weight

About how much does 1 gallon of aquarium water weigh?

About 8.3 pounds, so tanks are heavy.

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  1. About 1 pound
  2. About 25 pounds
  3. About 8.3 pounds ✔

Why: Water weighs about 8.3 pounds per gallon, so even a small aquarium is very heavy. The floor and stand must be strong, level and stable before you fill it.

Huh, didn't know that: A 10-gallon goldfish setup with gravel weighs almost 100 pounds.

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Why was the fish so easy to weigh? It had its own scales.
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References

Answer: About 8.3 pounds. Water weighs about 8.3 pounds per gallon, so even a small aquarium is very heavy. The floor and stand must be strong, level and stable before you fill it.

  1. Merck Veterinary Manual (pet owners): Providing a Home for Fish www.merckvetmanual.com/all-other-pets/fish/providing-a-home-for-fish
    1 gallon (3.8 L) of water weighs 8.3 lb (3.8 kg)
    Checked 2026-10-11.
  2. Gold Rush: A Kid's Guide to Goldfish Care (Univ. of Florida, Texas A&M extension) extension.rwfm.tamu.edu/wp-content/uploads/sites/8/2013/10/Goldrush-%E2%80%93-A-Kid%E2%80%99s-guide-To-Goldfish-Care.pdf
    Your aquarium will weigh almost 100 pounds once it is full of water and the gravel has been added!
    Checked 2026-10-11.

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