Before buying fish, read how to cycle a fish tank: UF says a new biofilter takes six to eight weeks. Then how many fish per tank, acclimating new fish, water changes and water parameters. And please read why you never release aquarium fish.
How-tos and explainers
Learn
How to cycle a tank
The nitrogen cycle and a step-by-step cycling plan from University of Florida fact sheets.
Learn
Water changes
Water-change advice from several sources side by side, and a safe routine.
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How many fish per tank
The inch-per-gallon rule, where it comes from, and the questions to ask before adding fish.
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Acclimating fish
Acclimation steps and quarantine advice from the CDC, UF and Aqueon.
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Water parameters
Each key water parameter, its safe range per UF and Aqueon, and why it matters.
Learn
Don't release fish
Why released aquarium pets become invasive, and how to rehome them responsibly.