Hi, thanks everyone.
Yes I think PFK is still down - I can't find it. Hi erk628, yes I have an API test kit and the water parameters are fine. I live in a high pH area (8.2) and I think some of the fish struggle with that. I always buy them from local pet shops though with the same pH. Deaths have gone down a lot recently ( I was loosing a fish every couple of months) but I've now learned what NOT to keep - bettas and guppys. Sadly the most beautiful fish!