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SESK: Stuff Everyone Should Know · sesk.info/fish-tropical-water-temp

Tropical aquarium fish need water kept near what temperature?

About 77°F (25°C).

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  1. About 60°F (16°C)
  2. About 95°F (35°C)
  3. About 77°F (25°C) ✔

Why: Tropical fish come from warm waters and need their tank kept near 77°F. Most homes are cooler than that, so tropical tanks need a heater. Fish from cooler places do better at lower temperatures.

Huh, didn't know that: Leaving aquarium lights on 24 hours a day stresses fish; they need a day and night cycle.

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Why did the tropical fish love the heater? It was a real fan of warm welcomes.
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References

Answer: About 77°F (25°C). Tropical fish come from warm waters and need their tank kept near 77°F. Most homes are cooler than that, so tropical tanks need a heater. Fish from cooler places do better at lower temperatures.

  1. Merck Veterinary Manual (pet owners): Special Considerations for Fish www.merckvetmanual.com/all-other-pets/fish/special-considerations-for-fish
    Tropical fish need water kept near 77°F (25°C), while species from more temperate areas do better at lower temperatures.
    Checked 2026-10-11.
  2. Merck Veterinary Manual (pet owners): Providing a Home for Fish www.merckvetmanual.com/all-other-pets/fish/providing-a-home-for-fish
    Fish need a day/night cycle for optimal health.
    Checked 2026-10-11.

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