I have got a pair of lovely Kribs, they are one of my favourite fish in my tank, and over the past week the male has become unwell. The first thing that I noticed was that he is not shutting his mouth, and now his eys appear to be bulging. All my other fish seem o.k. including the female, but he seems to be getting worse. I have not done anything different in the tank, I always do a 30 percentish water change about every 10 days and change / wash filter sponges as instructions. The only thing I did notice is that the fine filter sponges were extra dirty on the last change. Reading information I can find I have put it down to poor water quality and treated with King British Bacteria Control, but have seen no improvement yet. Does anybody else have any ideas? I'm really worried, I don't want to loose him!