UPDATE 3

Right so on Thursday I put the sick/bullied/worn out fish in a tank on his/her own which means I have three goldfish merrily swimming (or not) about - Beauty in 92 litre, Chris 2 in 22 litre, Chris 1 in 16 litre . I havent been able to get to the lfs so they have not been treated with anything except really clean water and peace and quiet.

The sickest of the bunch (Chris 1) is definately showing signs of improvement today. She is not lying on the gravel half as much, swimming about the tank more and is more interested in her food too.

Her tank mate (Beauty) swims about all the time apart from nightime when it rests on the gravel, so they all seem to be getting better.

I thought I would keep them apart for a month, but then what? Chris 1 is only in a tiny tank so she cant stay in there for ever and I cant get a new tank. Would it be worth trying them all in together again and see what happens? Only other thing I though of is put Chris 2 (who has already been ok) and Beauty (who was "nudging" ? trying to mate with Chris 1 in together and put the harassed Chris in thr 22 litre.

If it is mating behaviour that has caused this - how long does it usually last for and how often is it likely to occur? I have had Beauty and Chris 1 for about 18months I think and never had problems before.

Diana I am really glad the goldies are getting better - theyre great fish arent they and do seem to have personalities (or is that just me?? )

If it were me, I would try them all in the big tank again, but make sure that they are all 100% fit and well before you do. Perhaps the sickest of the bunch might need a bit longer apart?

If it doesnt work out then whoever is the bully(or randy) one I would put in a tank on his own. The 22 litre tank is the best option you have for that isnt it?

I suppose you could keep an eye out on ebay at some time for another decent sized one and in the meantime just keep a close eye on the water

Well I'm glad to hear that there's some improvement, Diana. It's annoying though that everything has been fine for so long and now this - I've just been watching my Angelfish chasing the Pearl Gouramis around...