Itchy Fish?

[ciderhoover]

Hi everyone.
 
I could really do with some advice.
This morning for the first time I have noticed my Mollies and my platys (but not my Danios) Itching themselves against the heater wire.
I then did a 50 percent water change, added aquarium salt and a general tonic.
My water testing kit says everything is fine with the water.
They are still doing it. Is there anything else I can do? or just give it some time?
There doesnt seem to be anything else wrong with them and they all look ok and are eating.

 

[NickAu]

What are your water Parameters? PH KH GH temp?
 

 
a general tonic.

What " tonic" did you use.
 

 
They are still doing it. Is there anything else I can do? or just give it some time?

Look closely at each fish, do you see tiny white spots on then? 

 

[ciderhoover]

Temperature 25.
I cant see anything on any of the fish, apart from where they have been scratching their scales.
ph was 7.2
gh 8.d
o.d was the KH .
 
I used Love Fish, Heatlh Guard.
I was thinking of getting an internal parasite treatment today and changing the carbon filters.
Thankyou,