Why do some zebrafish have long fins and others don't?

There are several different varieties of zebrafish... long finned, short finned (the natural wild type), striped (natural) and speckled, as well as albino and "pink" and "blue." All are merely genetic variants of the same species. They can all interbreed and you can do genetic experiments to determine dominance of the various traits. (i.e., are long fins dominant over short fins? etc. ... more