Do you only have the one male and female guppy in that tank? I think one more female would make him REALLY happy. And One fake plant next to the bubbly tube thing would look cool. Just a suggestion.
nice pics, big zoom ups may just need to bring the camera a tad back to make it more clear. good guppies! With the kb question, I use a BMP to JPG converter and it makes 500kb pics to 5kb pics without loosing quality. At least not to the human eye. 8)