About goldfish compatibity again..plz help?

I am from west bengal,India and here i have seen people breeding goldfishes and angels and swordtail etc all tropical fish in same temp. tanks..so if i put those in my tank, will temparature issue wil b a factor? i will use heater anyway in winter when temp goes to 6 degree C in my place...suggest me if i can put some angels or catfish wth goldfish?