Don't shoot me for using Wikipedia as a source, but the info is pretty much spot on.
https://en.wikipedia.org/wiki/Himalayan_salt
IMO most Himalayan salt is no different than salt sold as Sea salt. Both primarily consist of Sodium chloride (approx. 98%), although some labels only list sodium. The remaining 2% consists of trace minerals. The Nature Quest brand appears to be marketed for human consumption, so unless the package that you bought is specifically for bathing, and includes added fragrances etc, it will be fine for your fish.