The comet goldfish can be distinguished from the common goldfish by its long, single and deeply forked tail fin. Comets with yellow, orange, red, white, and red-and-white coloration are common.

The red coloration mainly appears on the tailfin and dorsal fin, but can also appear on the pelvic fin.

The Comet is more active than most other goldfish breeds. It is not unusual to see a Comet dashing back and forth in his tank, racing around in a playful manner. Due to the comet's hardy and active nature, and the relative ease in caring for them, they are the breed best suited to ponds and outdoor pools. They are often kept with koi in outdoor ponds. Comet goldfish have a natural life span of 7 to 14 years and may live even longer in optimum.

Due to the relatively inexpensive prices of comet goldfish, they may be used as prizes in carnivals and fair or used as bait and feeder fish.