Different habitats and eating habits. Different habitats: Carassius auratus is a kind of bottom fish, which is widely distributed in ponds, ditches, streams, rivers, lakes and swamps all over the country. Grass carp is a pelagic fish, which likes to live in ponds, streams, rivers, lakes and reservoirs and coastal areas with many aquatic plants. Different feeding habits: Carassius auratus mainly feeds on plankton, aquatic plants and algae. Grass carp is omnivorous. Besides algae, it also eats some small fish, shrimps and snails.