ok thanks, i hadnt done a water change in 10days when i noticed it, i did a 50% change and its still cloudy but doesnt look too bad, and i think the nostril is ok, probably was some glare in the pic.
But another weird thing, another of my Polli males is acting weird and has been for some days now.
He is very very light colored, just like he got when he was introduced to the tank, almost white, like he is very stressed.
But he is not at all stressed, he is very calm and floats by the surfice completle motionless, didnt even mind me touching him

But other than that and the light-color, he looks fine.
Both polli males came from the same person and got into my tank 2 weeks ago. They came with one female which is 110% fine and healthy.
I dont have a hospital tank atm but it looks like i will need one, i am most worried with this being something that the others can get ?
I have been noticing my Clown Knives scratching on the sand regularly in the last few days, could it be related ?

Water quality is fine.