I think you need to give the experts a lil more info. I use it to help rid and control parasites that may lurk in my tanks. If you got a sick fish you may want to list symptons.
It's a treatment for the ich parasite. In concentration it will destroy the parasite. Other uses include treatment for nitrite poisoning. The nitrite blocks absorbtion of oxygen in the hemoglobin. Treating with salt can alleviate this. Do you have a problem with your fish?
I wouldn't use it all the time unless there is a problem that can be specifically treated by salt, such as ich like the above post said. Some people use a tonic dose with all their water changes, but to me it seems unnecesary
yea my oscar. i posted a thread about him. now he has heavy breathing. and he is just laying around. the salt that i bought said it helped breathing through to gills and somone i no recumended it to me. so im tryin it