How to recognize stress

I am currently VERY slowly adding salt to a ten gallon to treat for ich. Every time I add some, the fish race through the tank as if they are on crack or something. It lasts about ten minutes and then they calm.

I have mixed the salt (20 teaspoons) in a 1/4 gallon of water and am spooning it in via the filter, maybe 10 spoonfuls per hour (last time it took me 24 hours to get it all in, and no fish died). Water is fine (o amonia, 0 nitrite, 5-10 nitrate.

Is this racing a sign of stress? They really sort of bounce of the wall for ten minutes. And then they are perfectly fine. I took out the decoration, so they won't hurt themselves (I will put it back in when the salt is in) Should I go even slower?

10 gallon. 1 swordtail, 2 mickey moons, 2 platies, 1 cory. I know it is a bit overcrowded but the mickey are in this tank because I needed a hospital tank for another platy with fin rot (so I took the mickeys out of that tank). I have left the tank alone for now and will add the rest of the salt tomorrow. I think I have about 1 teaspoon a gallon in there now. Fish are doing well.
The platies (all 3) are all meant to go in a 29 gallon that is currently being cycled... but the ich screwed up the whole plan...

L.

Faiz see original post:
amonia 0, nitrite 0, nitrate between 5 and 10.
I tested again this morning, there is a trace of nitrite in the tank, but lower than .25.

I think I dissolved it enough: used hottish water to dissolve the salt and then let it sit for a few hours to cool off. (I have finally learned a bit a patience...)

I added another ten spoonsfulls this morning and they stopped racing a lot faster (maybe 2 minutes of bouncing) so it must have been a reaction to the fist bit of salted water added to the tank... I am going to take it even slower though...