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SESK: Stuff Everyone Should Know · sesk.info/fish-chloramine-what-it-is

Many cities treat tap water with chloramine. What is chloramine?

Chlorine combined with ammonia. Both are toxic to fish.

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  1. A vitamin added for fish
  2. Salt added to soften water
  3. Chlorine combined with ammonia ✔

Why: Merck says most city water has chlorine or chloramine, a mix of chlorine and ammonia. Both are toxic to fish and to the helpful bacteria in your tank, so every bit of new water needs treating.

Huh, didn't know that: Merck says dechlorinators are fast acting, easy to find and inexpensive.

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What is a fish's favorite instrument? The bass guitar.
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References

Answer: Chlorine combined with ammonia. Merck says most city water has chlorine or chloramine, a mix of chlorine and ammonia. Both are toxic to fish and to the helpful bacteria in your tank, so every bit of new water needs treating.

  1. Merck Veterinary Manual: Providing a Home for Fish www.merckvetmanual.com/all-other-pets/fish/providing-a-home-for-fish
    Most city water is treated with chlorine or a combination of chlorine and ammonia (known as chloramine)
    Checked 2026-10-11.
  2. Florida Sea Grant: Q&A, How to Keep Your Fish Tank Safe During a Power Outage www.flseagrant.org/qa-how-to-keep-your-fish-tank-safe-during-a-power-outage
    Many municipalities use either chlorine or chloramines (chlorine combined with ammonia).
    Checked 2026-10-11.

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