Hi. New to the forum and looking for advise. I purchased a pair of fancy Guppies last week and the female already died and the male is in obvious trouble. They appeared to be in very good health as were all the other Guppies in the tank where I purchased them. My tank is 28 gallons and well established (3 years) with Neons, Glowlight Tetras, Red Minor Serpaes and Corydora catfish. They have all been in the tank for at least 1 year and are all healthy. The ph is around 7.2 and the only water measurement high is general water hardness at 180ppm. Any ideas what I should look for that may have affected just the Guppies? Thanks in advance.