For 80 gallons which is standard size of 48"x18"x22". You can keep mostly dwarf specy bichirs and maybe squeeze one Endli or Ornate in there. If you stick with dwarf species such as senegals, polli palmas, palmas palmas, delhezi, and albino senegals you'll still have a nice setups. You could keep 8-10 of these if you overfilter your tank and do weekly waterchanges.