For reference:
Rainbowfish can take very high levels of salt; around 17ppt.
I had my clown loaches at 2.5 tsps salt for almost 3 weeks with no ill effect. Temperature 82* for ich with that. Heavily planted tank as well.
Make sure you add an airstone when treating for ich and raising the heat, especially with rainbowfish.
Roan
Rainbowfish can take very high levels of salt; around 17ppt.
I had my clown loaches at 2.5 tsps salt for almost 3 weeks with no ill effect. Temperature 82* for ich with that. Heavily planted tank as well.
Make sure you add an airstone when treating for ich and raising the heat, especially with rainbowfish.
Roan