do fish need salt?

Question
hello. i was just wondering, do fish need salt? i have a 5 gal tank with one male betta and a 10 gal tank w/tetras and cories and at the store they said to add salt and sold me a box of aquarium salt. my question is,, is it necessary? will it hurt? or help? or make no difference?

thanks

Answer
Hi Heather,

This is a tricky question. The answer varies depending on who you ask, but in my personal opinion, most freshwater fish do not need salt. Your betta doesn't need salt, and your tetras and corys don't either.

The fish that do benefit a whole lot from salt are certain livebearers, particularly mollies - who many experts agree are actually brackish fish, not community fish, as they are marketed.

Here's more on that, if you're interested:
http://www.wetwebmedia.com/FWSubWebIndex/mollies.htm

While it is possible to keep mollies in hard and alkaline, entirely fresh water, they will thrive with the addition of salt - so I see no reason to deny them of it! Keep them with other salt tolerant livebearers such as guppies, or try them with glassfish perhaps...but a molly specific aquarium is actually a very attractive sight.

Salt is beneficial when fish are thrust into a new aquarium that has nitrite registering. Salt reduces nitrite toxicity. It also encourages the slime coat to develop, which makes it helpful when you are treating for ich. In fact, salt can be used with increased temperature to treat ich. You can read more about that at the article below:
http://www.cichlid-forum.com/articles/ich.php

So in short, while salt can have a useful purpose in fishkeeping, it is not needed on a regular basis - unless you are keeping brackish fish. In that case, marine salt is the salt to use (which has buffers and trace elements, not just sodium chloride). If you are using salt medicinally, for example to treat nitrite toxicity or ich, then by all means - get yourself some kosher salt, ice cream salt, pickling salt, sea salt, any kind of salt besides table salt...it's cheaper than aquarium salt, and it is exactly the same! Pure sodium chloride.

This article is one of my favorites, and it describes salt in aquariums better than I ever could...do bookmark it!
http://www.aquariumboard.com/forums/articles/4770.htm

I hope that helps. Take care,
Nicole