i just giggled at the topic tags
ok.. much has been asked about how to sex goldfish. this is my view on how to tell male from female and visa versa..
breeding stars on pectorial fins as well as on gill plates, around eyes and sometimes all over the head. the pectorial fins of a male, on top are rather thick so they can carry their manlihood with pride
this guy, he's got breeding stars only on pec fins. sometimes breeding stars can be seen on his gill plates, but most often, he displays them only on his pec fins:
the vent of the male goldfish:
notice that it's smaller and taller.
her pectorial fins on top are thinner and there are no breeding stars:
the female goldfish vent:
notice how it's wider, stretched like more of a circle or in this instance, kinda like a triangle or diamond?
you can also tell the difference between a male and female goldfish when they're turned upside down by their bellies between the ventral fins and how they are attached to their bodies.
normally on the male goldfish, the space between the ventral fins is slightly more concave. on a female, it's quite full and round. the male in that area tends to be thinner where the female can carry a rather lovely and smooth belly. if you go back to the belly pictures i posted above you will notice the difference i mention here.
hope this helps a few members to be able to sex your goldfish with ease