congo tetras

http://www.youtube.com/watch?v=Q4HdI7l4XZY&list=UUfOf7CYNr2PVpat8521pykg

Hi i'm Mark and i'm new to the forum   I was wondering if anyone here could help me. I recently purchased 4 juvenile Congo tetra's from my local fish store, I was told they were male but i'm not 100% sure. They are not currently showing any signs of coloration or fins developing, Hopefully...