That is Gymnocorymbus ternetzi or common names Black Skirt Tetra or Black Widow Tetra. It is included in our profiles, just click on the shaded name to see the info on requirements, etc.

Byron.

 

it was best to ask as could have spent hours searching to identify it.,
I just had a look at the profile... but is it compatible with neon tetras, platy and guppy?
thanks anyway.