Fish can tolerate higher levels of salt than most would think. A lot of people even dose their tank with 1 tbs / 5 gal regularly, although I would recommend against it. Anyways, your fish would be able to handle the 2 teaspoon per gallon for a short period easily, and it would help with the ick, but if the treatment you have already started is working, I guess stay the course. Just know that if you have to you can bump up the salt. I have a bgk and Ive done both before with no problems (both 1 tbs / 5 gal and 2 tsp / 1 gal).