guppies are amazonian, aren't they?
Koi are just coloured carp. The only wild ones I have heard of are ones that have been released. There is a large orage and black koi that lives in the bay that I live close to. Tried to catch it many times, never a bite. Koi were developed by the japanese as decoration that were only to be owned by the emperor or japan. Carp are the same thing as koi except less colourful, many people call koi "koi carp". Carp were also developed by the japanese, but are found everywhere now because of something called the "carp act". This took place around the time of WWI. It was part of a beautification process that all ponds and rivers and lakes in the U.S. were to be filled with carp. Canada soon followed (I am just going by what my school history book told me).
No idea about goldfish, i know there were developed by either the chinese or japanese.
In the wild, bettas live in rice paddies and other places with stagnant water. In the wild, all males resemble females because they have short fins, the males do not have all that colour either. I will include a pic. of wild male and female. Bettas and guppies are not generally wild caught since they can be bred easily with nice fins and great colour.
I hope this is what you wanted to see. Very interesting stuffm eh. And if i am wrong at all, please correct me.