A friend of mine has a 90 gal
African Cichlid tank and it's beautiful. Just make sure you don't mix the Africans with the S. Americans. (I think that's what they are) I have a 55 gal
community tank. You're guppies and mollies would be OK in a community tank IMO
. I try not to get troublemakers but sometimes a couple of mine get a tad aggressive with other fish. I have gouramis, eartheaters, tetras, a green severum, a pleco, and a striped rafael catfish. One of the gouramis is a Neon Blue Dwarf Gourami and he's probably the most colorful fish in the tank. There are some beautiful freshwater fish out there. You just have to decide what kind of tank you want. Plus, I agree with MKCKEE, sand is great! My fish love it!