Salt.....is too little to much?

So i noticed when my parrot fish get stressed they get black marks on their body, and when they are not stressed the marks disappear (i know.....nice early warning system). So i have noticed since i have stopped putting salt in my tank, the 1 parrot fish has started to get these black marks again.

I do my weekly water change (20-25%), i do my monthly filtration change (carbon and ammonia remover), the water temp is perfect at 27 degrees, everything else is perfect, so the only conclusion i have come to is due to the stoppage of salt treatment once in a while, but here is my question.......

will it be good or bad if i throw in salt every now and then (ie: when i do water changes)?

 

Salt does not leave a system - unless you remove water from the system....not knowing what your salt level is will eventualy lead to a dangerous situation - get a good hygrometer and make sure....

Parrots are hybrids of Central American cichlids,in nature they (the "parent" species) would not encounter any salt in their natural habitat,but 50-100gr/100liters of water wont be to much...