Goldfish are generally active and friendly fish, which can easily recognize their owner. It is not common to see Goldfish swimming from one side to another in an aquarium tank, getting excited and splashing the water vigorously during feeding time. They are also notorious for being a heavy feeder whereby they will not stop eating and continue to stuff food into their stomach until they die.
Goldfish should not be kept with other fish species in a community tank. First of all, they have different requirements when it comes to water condition because as a cold water fish they can only thrive in waters with lower temperature around the region of 18 degree Celsius. Even if you managed to find tank mates to live with them, this is still not a good option to take because bigger fish will often pick on your pet resulting in injuries. Even plecos, which are always present in any aquarium setup to collect fish waste, will attack your goldfish resulting in torn fins and raised scales. Being a heavy feeder also means that their feeding regime will eventually spoil the water quality in the community tank.