Thanks for the advice, I'm new to keeping fish and had no idea that goldfish needed so much room!
Getting a water testing kit is on my list of things to do, though I have had it tested by a pet shop recently and they didn't have any concerns. I do my regular water changes etc and the fish seem happy enough, although I do know someone with a pond, so I'm thinking of re-homing one or two of the males.

The only thing I had to hand was an old fish bowl, so that's where Princess is at the moment. With regular water changes of course.

Knowing what I know now, I feel bad for ever having fish in a bowl, but I don't have much choice at the moment :(

Help! My male goldfish are so eager to breed they're bullying the female to death :(
I have 4 males, which all look like they're ready to breed, they certainly all have the tubercles on their gills.
I also have 2 females, but only one is old enough to breed. This poor fish has been chased and nibbled so much by the males that I have had to remove her from the tank. The majority of her scales on either side have been nibbled away and I don't know what to do with her :S is there some medicine I should give her? And is there anything I can do to stop the males being so, er, horny??

Unfortunately I learned the hard way, but I'm glad to see that I'm now doing most things right :)