Just to add to the stocking 10g. Tetras (any type), cories (any type), need to be kept in groups of 4. There actually aren't alot of tetra that work well for the 10g. Many will work, but they will take up all the stock. Ember Tetra
will work fine. Lemon Tetra
will work only if they are the only fish in the tank. Neon Tetra
don't work in a 10g imo (and several experts opinion also). Black Widow Tetra
and Bleeding Heart Tetra
get way to big for a 10g.
Dwarf and Pygmy cories will work just fine with other fish. Many cory schools are to big, though. Such as albino ad many others. Research is the best preventative to desaster.
Danios have to be kept in schools. Most danios, due to their activeness, are not suitable for a 10g. Celestrial danio will work, but those can be pretty expensive.
People have mixed opinions about mollies and platies being in a 10g. Some people say platys don't work, and some say that mollies wont. I, personally, wouldn't use either. If there is a question, I would choose the most cautious side of the argument.
What kind of danio do you have? If you post a pic, we could probably tell you.
Hope this helps!