Oscars are New World cichlids, coming from Central/South America so arn't African.
You could only keep ONE oscar in 58 gallon with nothing else, maybe a pleco.
If you want to keep two oscars, i recomend getting a 120 gallon, but if you want to keep other tankmates that will survive with oscars, 150 gallons is better
upside down catfish.i had one it played alot and then it just died for no reason but it awesome really supper cool awesome i think i might get another KO KO KA Kaboo