No. No. One Oscar is too big for a 55. One fire eel is too big for a 100. One chocolate cichlid is too big for a 55, I think they get as big as Oscars. 3 Geophagus may be workable depending on the species. Giant Danios are thin, so they don't add too much bio-load, but in a 55, if you had nothing but giant danios, twelve would be the waste limit. They would look pretty cramped once they got to a good size. They are fast fish, you know? I do like your taste in fish, friend. That would be a pretty good arrangement in a larger tank.