SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/fish-check-new-water-temperature

Before pouring new water into the tank during a water change, what should you check?

Its temperature, so it matches the tank.

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  1. Its temperature ✔
  2. Its color under a flashlight
  3. Its weight on a scale

Why: Purdue's 4-H guide says to check water temperature before adding it to the tank. Fast changes in temperature, pH and hardness can stress fish and make them sick.

Huh, didn't know that: Purdue says if the new water is too cool, warm it by heating a small amount and mixing it in.

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What did one fish say to the other? If you keep quiet, you won't get hooked.
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References

Answer: Its temperature. Purdue's 4-H guide says to check water temperature before adding it to the tank. Fast changes in temperature, pH and hardness can stress fish and make them sick.

  1. Purdue Extension 4-H 447-W: Aquatic Science helper's guide www.extension.purdue.edu/4-H/_docs/4-h-447-w.pdf
    Check water temperature before adding it to the tank.
    Checked 2026-10-11.
  2. Texas A&M AgriLife Extension: Gold Rush, A Kid's Guide to Goldfish Care 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
    Fast changes in temperature, pH, and water hardness can stress your fish
    Checked 2026-10-11.

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