I'm getting some new tetras and I was thinking, I only study guppies. I don't ever study tetras. The tetra I have now was my first fish in the tank I now use for guppies. I call it Dusk because it its a glow tetra I think. I'm not sure. On a dark background he is black with an orange stripe. Without the background he is clear with an orange stripe. I don't know why I'm calling it a he! How do I tell a male from a female? Will they crossbreed with my guppies?