Thanks all.
I have been to the LFS today and picked up a powerful internal filter (looks a bit cumbersome in the tank but hey-ho) I am hoping that this will assist with water qualiy but as I mentioned my stats are fine. The plecs seem to like the increased flow in the tank though so that's good. All the other fish in the tank look fine - not even the slightest sign of disease so I am puzzled at his death. I did have an outbreak of whitespot in November that took a while to clear up but all has been clear for quite some time now. I don't think it was old age cos he was quite small - smaller than the others in the shop. I am gonna keep a
really close eye on the tank to see if anything develops.
I also bought another 174 today. He's just in quarantine now. Not quite as striking as Louis but still a fabulous fish. I just couldn't resist. I'm going back next week to look at some 46's that the owner will be bringing in. He got 30 in the New Year and they are currently at his house. I know I'm not going to be able to resist when I see them........
This obsession with plecs definately equals an empty wallet.