I've heard some people say to add some salt to a freshwater aquarium to help keeping my fish healthy. Is there any basis for this claim?

Some background on my tank:

20 gallon long freshwater planted aquarium with gravel substrate, a few rocks, a large piece of wood and an Emperor 400 for filtration. My fish include 8 platies (they reproduced), 1 balloon molly (two died, which is sad), 8 tetras, a lot of cherry shrimps, 3 amano shrimps, 4 African dwarf frogs and a few dwarf crayfish. I'm thinking of adding a vampire crab and a small dry zone for it.

1 Answer 1


I don't have any links, however I do have quite a few year's of experience keeping freshwater aquariums. When I first started I didn't know about the salt. And I noticed on odd occasions whenever I introduced new fish, or during season changes (especially spring) my fish would catch ich. And if you had it, you would know how annoying it is. However afterwards I decided to start adding one teaspoon of salt for every three gallons. And since then not a single case of ich outbreak occurred. It might be either salt that kept fish healthy enough to not get ich, or that I had more experience. I don't know, but just thought I would leave my two cents with you.

  • The ich parasite (most invertebrates actually) is very sensitive to salinity. One of the best cures for ich in the saltwater trade (more properly called crypto) is hypo-salinity. If done properly, the fish can tolerate it just fine but the parasite cannot. I'd imagine the opposite case is true for the freshwater variety.
    – Gary
    Commented Mar 21, 2015 at 16:59
  • @Gary now I am always adding salt, and have observed no issues whatsoever. Actually I have noticed that betta and guppies are extra vigorous and live much longer thanks to salt. But then again, it just might be because I have gained more experience compared to when I started fish keeping
    – Quillion
    Commented Mar 21, 2015 at 17:21
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    @Gary. The FW and SW ich parasites are unrelated. Freshwater ich is completely unaffected by any therapeutic level of salt that a person would add to an aquarium. They are however easy to treat using elevated temperature alone. At the same time there's quite a bit of anecdotal evidence that salt can help boost fish's immunity and metabolism, so the reduction of the occurrence of ich could be related.
    – Jestep
    Commented Mar 27, 2015 at 17:01
  • @Jestep I realize they're completely different (hence correctly ID'ing it as crypto) but was guessing since SW inverts are super sensitive. I should've known that since everything FW is considerably hardier that it wouldn't be the same.
    – Gary
    Commented Mar 27, 2015 at 17:51

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