Angelfish and goldfish are both freshwater fish, and many hobbyists love the idea of a tank containing multiple species. However, these fish have vastly different needs and should not be housed together.
Goldfish are coldwater fish that require water temperatures between 62 and 72 degrees Fahrenheit, while angelfish are tropical fish that require over 75 degrees. This alone is sufficient reason to keep the fish separate, as either species can stop eating, become ill, become aggressive or die if temperatures are not in the correct range.
Goldfish are generally peaceful and can live in large groups. Although angelfish can be housed with other angelfish, they tend to be aggressive. They are extremely likely to prey on goldfish. Thus, even if it were possible to safely house angelfish and goldfish in the same temperature water, the angelfish would be likely to prey upon the goldfish.
Many people keep angelfish and goldfish in small enclosures, but these enclosures can limit growth and lead to health problems. Both fish species require ample space. Angelfish require at least four gallons of water per fish, and goldfish need five to 10 gallons of water per fish. Because goldfish can grow quite large, adult goldfish might need 20 to 30 gallons per adult fish. Housing the fish together could result in overcrowding.
Angelfish and goldfish can eat many of the same foods. Both are omnivores, but angelfish require more protein. Bloodworms, brine shrimp and mosquito larvae are excellent foods for both fish. Chopped vegetables such as mustard greens and collards are also excellent choices, but they should be fed to goldfish in higher quantities.