That's the fishy cheers guys incidentally now i know exactly what they are i can sex them
'The male's dorsal fin is more narrowed and more pointed. Also, the male's frontal portion of the "skirt" or anal fin is noticeably broad while the female's "skirt" tends to run parallel to the stomach line. A mature female is also more plump.'
based on this i would say the top one is female whilst the bottom one is male
Incidentally i have had 3 seemingly healthy guppies die 2 with no visible symptoms my water tested fine - 1 had a damaged scale area like a bite - i was thinking it could be my red tailed black shark as he chases the other fish round on lights down and i've never seen these coloured skirt tetras do anything - but apparently there are fin nippers....