Is this Hole in the head disease?

[Gheko]

I find out the nitrates Are way over the limit! That's what i intend to do: 50% water change(300 liters!!) cleaning of the filter (Teo pratiko400 from askoll) and replace carbon filtrating material with resin, change of food Any suggestion for right diet?? Note: where i keep this tank i got no water heater so i will mix bucket with 50% boiling water with cold tap water. Is that ok? Thak's from Sicily

 

[SkySouza]

I have a similar thing going with a discus but my water params are fine. ph was 7.5 tho could this be the cause. I have been using tap and the ph is high close to 8. time to start using drinking water...

 

[Gheko]

That's It! Done, changed around 300 liters of water, cleaned sponge in the two filters and added some resin in one filter. I find out that the tap water is pretty good Ph 6.5 and NO nitrates!
I'll get some more water tested today and I wll post the result.

The fish looks much more healtier today!! the hole seems like is starting to heal keep finger crossed!