Well if the water is clean and water not too hard rams; esp gold rams are really nice. They aren't super large but still quite nice. If the water is slightly acidic apistogramma nijjensi are a favorite of myself (though 82 is pushing it a bit so maybe not). For the bottom 82 begs sterbai cory (if you get a cory); otherwise another favorite of myself are L204 (pleco); or the tank might be large enough to support a gold nugget (pleco). Another favorite are kuhli - 20 or 30 kuhli loaches. For the top rummy nose tetra are an active tetra that like warm waters. Conversely cardinal tetra (more middle) if you want something that sits around all day looking pretty. Swordtails - well you only need 1 male and 1 female to get as many as you want - i keep a tank with some swordtails and guppies and while my male swordtail is closing in on 5 years and looks it - at the end of the day they are not the most interesting fishes one could imagine keeping.