Goldfish are not particularly aggressive but given that they are omnivourous they will certainly eat other occupants in their envirionment if they are small enough to be swallowed.
Note: There are comments associated with this question. See the
discussion page
to add to the conversation.
It is not being aggressive it is just being a goldfish. Goldfish will eat any fish small enough to get into their mouths. They do not recognise their own fry(youngsters) so are quite likely to eat...
There ancestors are gold... different colored traits over time dominated the classic gold color, while in some breeds, the gold color will dominate during the trait selecting process
Because it will be matingg season for your goldfish'swich means one of them is a boy and the other a girl.the girl will be the one with the mostly wided V tail, butremember goldfish lay from 15-20...