Hi LyndaB,
Thanks for the reply.
I think it is the Betta, in the UK they're called Siamese Fighting Fish.
It was a new Fish and added to a 12 Gallon tank alongside 4 Golden Bards, 4 Mollies and 2 Golden Panchax.
NO3 is 0.1, NO2 is 0.2, PH is 7.2 and KH is 6.