Aquarium salt: when to use it and when not to
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The short answer: aquarium salt (sodium chloride) is a short-term tonic, not a permanent part of a freshwater tank. Used carefully and briefly, it can help fish under stress and support treatment of some external problems. Used as a routine, always-in additive, it does more harm than good. It offers no benefit to a healthy planted community tank, many live plants and some sensitive fish do not tolerate it well, and it does not evaporate out, so it only leaves through water changes. Always dose to the product label, and when in doubt, use less.
What aquarium salt is (and is not)
Aquarium salt is plain sodium chloride, sold for freshwater tanks, such as API Aquarium Salt and Fluval Aquarium Salt. It is not marine salt mix, which is for saltwater tanks and contains many other minerals, and it is not the same as the cichlid mineral salts used to harden water for African cichlids. See the full range in our salt collection, and read the label so you buy the right one for the job.
When it can help
- As a short-term tonic for a stressed or recovering fish.
- Alongside other care for some external issues; follow the guidance on the medication and salt packaging.
- As a brief bath in a hospital tank, kept separate from your display.
In every case it is a temporary measure. When the fish recovers, the salt should leave the tank gradually through normal water changes.
When to leave it out
- Planted tanks. Salt provides no benefit to plants and many species react badly to it.
- Sensitive fish. Some scaleless fish and certain catfish and loaches are more sensitive to salt, so many keepers avoid it with them. When unsure, ask us first.
- As a permanent additive. Continuously salted freshwater is not natural for most community fish and is no substitute for good water quality.
Use it safely
Dose strictly to the label, dissolve the salt in a cup of tank water before adding it, and never guess. Because salt does not evaporate, adding more at every top-up will slowly raise the concentration without you realising, so only replace salt for the water you actually remove. A test kit and a proper quarantine setup are better first tools for a sick fish than reaching for salt, and we keep the medications to match.
Related guides
Come and ask us
Fishkeeping goes better when a real person can look at your setup. Come into the store in Lethbridge, call us at 403-380-4506, or send us an email, and someone who keeps fish will help you get it right. Written by the team at Tropical Fish Imports.