Thanks all
I have a 90L - 20gallon tank with 2 angels, 1 ghost knife, 1 glass catfish, 1 flying fox, 4 rainbow tetras, 2 silver dollars, 1 kissing gourami, 2 flame gouramis and 2 neon tetras (use to be 10 but i believe this death rate is normal). I've lost 1 kissing gourami (from a dodgy shop...