What fish do i have..?

Hello i have lots of tanks and many many fish of all breeds and resentily i was given a 6 fish and im trying to find out what they are they look like small tetra's of some sort but cant find them anywhere i serch. they have orage up lower back fins shaped like a tetra front half of body is silverish and the back of the body and down to the back fin are a ink blue like out of a ball point pen.. very nice interesting fish love to be in groups the coclor on these fish are shiny not dull.If anyone knows what kind these little guys are that would be great.. i can send a picture if you think you might know what they are natasha.l.m@hotmail.com..please serious people only.i have been keeping fish for many many years justhaveing trouble with propar name of this one and could use some help..thank you everyone..