my tank has been running for about 7 months but only three months with a new external filter, but I test my water every day and do a 20% water change every week, I have tried many of the suggestions above but my plec still wont eat, I have now set up a hospital tank which I have left running for a weak and add 30% of my normal tank water to it, I have been told by my local aquatic centre that I need to separate him from other fish, my fear now is that the move to the new tank will stress him out and make things worse. my problem also now is that if I put my plec in the new tank the bacteria on the filter wont be sufficient and the break down of proteins will not be happening quickly enough and the nitrate is just going to shoot up, but if I leave the tank to settle any longer then I think my plec like you all say will die.