Fish Health & Disease, Freshwater Fish Care
Aquarium Salt in Freshwater Tanks: When and Why to Use It
Aug
Aquarium salt occupies a specific, limited role in freshwater fishkeeping — useful in certain situations, but not something every tank needs as a matter of course.
When Salt Helps
A low dose of aquarium salt can support fish recovering from certain bacterial or fungal infections and is well tolerated by species like mollies, which naturally inhabit brackish water in the wild — see our molly care guide.
Species That Don’t Tolerate Salt
Scaleless fish, many catfish, and most freshwater invertebrates like shrimp and snails are sensitive to salt and can be harmed even at doses considered mild for scaled fish.
Salt Doesn’t Replace Water Quality Management
Salt should never be used as a substitute for addressing the underlying cause of illness, such as poor water quality — see Understanding Aquarium Water Parameters first.
Dosing Carefully
If using salt, dose gradually and remove it through water changes once treatment is complete rather than leaving it as a permanent additive in a community tank containing salt-sensitive species.
