* Body shape: Males tend to be more streamlined and have a longer, more pointed dorsal fin.
* Coloration: Males are often brighter in color than females, especially during breeding season. They may also have more distinct markings.
* Behavior: Males are generally more active and aggressive than females. They are also more likely to chase and nip other fish.
Female Goldfish
* Body shape: Females tend to be rounder and have a shorter, more rounded dorsal fin.
* Coloration: Females are often less brightly colored than males. They may also have fewer markings.
* Behavior: Females are generally more docile and less aggressive than males. They are also less likely to chase and nip other fish.
Of course, there are always exceptions to the rule. Some males may be more docile than females, and some females may be more brightly colored than males. But in general, these physical and behavioral differences can help you tell the difference between male and female goldfish.