It's quite possible that it's got an internal parasite which has infected it's brain and spine.
is it feeding? Is it doing it all the time? If it is, I personally would isolate it, keep an eye on it then if it continues euthanise it.
It's not doing it all the time, but quite a lot, It looks as if it is playing.I think it is feeding,I only noticed it yesterday, can't see any white spots and it looks healthy.Thanks for your advice
Is it being picked on by the others? I've usually found that within my own tank that if one is ailing- the others will attack it, and if it's not rescued quick enough they'll kill it.
Hi BOO, just to let you know I have just had to take the barb out I have been to look at it, it was going mad so I did the best thing Thanks for your time.