Goldfish and carp are very similar. They are hardy, pretty, and usually long lived.
Good choice for aquariums because they are pretty civilized.
You might want to know category:
There is a "top 10 list" of killer disease of wildlife, +/- humans in the world. On the list is Spring Viremia of Carp Virus (SVCV) which more knowledgeable aquaculture professionals are aware of. This is a potential desimator of closely housed populations of goldfish and carp costing $$$$$
Mugshots are in file
The entire genome has been sequenced
There will soon be a very high tech oral vaccine
I have the reference links if you have an interest.