Well we've done tests on the tank now for 3 days and everything is perfect. I received the bigger interpet kit from ebay yesterday and did ammonia, nitrite, nitrate and ph and everything was perfect I'm so pleased. The blue platy seems a lot happier but the orange platy is still picking on the white platy. When it doesn't the white platy seems perfectly happy swimming around. Although it doesn't swim strongly its a lot better than it was, until the orange one starts picking on it again, so its back in the hospital tank bless it. Its top fins are up a little bit more but not as much as they should be and its bottom fins just sort of trail behind it, its a male so I don't know if that's just normal, there is a tiny little red dot on its anus but it doesn't look swelled so I don't know if that's anything. Its kinda thin but males are thinner than females aren't they, apart from that there's nothing else on it, its eating normally and perks up when its fed but it doesn't seem to be putting any weight on, surely if there was something really wrong with it it would have died by now wouldn't it? x