not to mention guppies, although in a nice way ;p

I would like to highlight that guppies, koi, goldfishes, siamese fighting fish, etc are not really hybrids in the genetic sense. These fishes maintain their normal gene pool and can revert to their natural morphology.

Things like parrotfish can never revert to their "wild" look because they don't exist in the wild at all, its created by Man by forcing two separate species (inter-specific as well as inter-generic) to hybridise through hormonal or other means. They are now doing it to many of the Synodontid catfishes.