Plecos or loaches like clowns or yoyos are usually good choices for big fish in a small-fish tank. They're plant-eating and don't bother other inhabitants. I would strongly recommend putting bogwood in your tank and providing lots of plants, and feeding algae and plants at least once a day. Loaches tend to school, so I would stick with the pleco if you're going to go this route. Alternatively, an angelfish community, with paired angelfish, some larger tetras like rummy noses or cardinals or congos, or some livebearers like platies or mollies, and some bottom-feeders like, again, loaches, plecos, corydoras (tiny!), or otos (even tinier!). Try to avoid going too small (stick with fish that are two inches or more), or else your tiny fish will become a snack for the angels. Some ideas for your tiny fish: Neon tetras Cardinal tetras Rummy-nose tetras Harlequin rasboras Dwarf rasboras Corydoras catfish Otoclinus Glowlight tetras Zebra danio (nippy) Black Skirt Tetra (nippy) Cherry barbs That's some of the most common ones. I would recommend visiting your local fish stores and picking and choosing which ones you like the look of, and then going home and researching all of them. A good source to start on research is the Aquarium Wiki.