What kind of fish can I add to Dalmatian Mollies?

I am a beginner aquarium owner with a 10 gallon fish tank. I have a filter and an air pump with 2 air stones, but I don't have a heater. My hood has a built in light, and it keeps the water at 72-78 degrees, normally in between. I know that mollies prefer Brackish water, and I was wondering if there were any kind of fish I could add to them. And do I absolutely have to have brackish water, I don't want them to reproduce a lot since I'm getting male and female. I have looked for answers, but I just can't find the right answer. Hope you can help! :)