I know I say this all the time, but I strongly believe 15 gal is the minimum size for a pair of rams. Even then, I don't think it'd be large enough to house tetras as well. If you want both rams and tetras, go with a 20 gal (possibly long?), with tetras such as neons, cardinals, or glowlights (5-7). If you MUST have only a 10 gal, the only fish I can think of that would work would be otos. With a 15 gal, maybe a betta and otos. Try to get a larger tank though, rams are much happier and more active with larger tanks (as are bettas...but no one really realizes it).