Get a bushy nose Pleco. They stay small which will be good for your tank. If you only want 6 or 7 fish that means you aren't interested in schools like cories, tetras, loaches,or rasboras?
You could do a pair of angels, 3 rainbows, 1 BN Pleco, and a spotted Raphael cat.
Or if you are interested in schools, you could go with 6 tetras of your choice, dwarf gourami, German blue ram, 6 cory cats, and the BN Pleco.
Or you could do some small cichlids like 1 each of festivum, rainbow, keyhole, and blue acara, with a redtail shark for a bottom dweller.