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SESK: Stuff Everyone Should Know · sesk.info/fish-fishless-cycling-source

A fishless cycle adds what instead of fish?

An ammonia source, such as ammonium chloride or a little fish food.

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  1. An ammonia source ✔
  2. Vitamin drops
  3. Aquarium salt

Why: Fishless cycling feeds the nitrifying bacteria without putting fish in toxic water. You test until ammonia and nitrite both read zero.

Huh, didn't know that: Once tests show no ammonia or nitrite, fish can be added safely.

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Why are goldfish orange? The water makes them rusty.
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References

Answer: An ammonia source. Fishless cycling feeds the nitrifying bacteria without putting fish in toxic water. You test until ammonia and nitrite both read zero.

  1. Merck Veterinary Manual: Management of Aquarium Fish www.merckvetmanual.com/exotic-and-laboratory-animals/aquarium-fish/management-of-aquarium-fish
    One method, known as fishless cycling, is to completely set up the tank but with no fish addition; ammonia is added
    Checked 2026-10-11.
  2. Merck Veterinary Manual: Management of Aquarium Fish www.merckvetmanual.com/exotic-and-laboratory-animals/aquarium-fish/management-of-aquarium-fish
    Once no ammonia or nitrite is present, fish can be added safely.
    Checked 2026-10-11.

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