Koi are just river carp (german carp) with color. All physical and internal features the same. Note the characteristic barbel at the corner of the mouth. They are also fertile and readily reproduce. A significant % of offspring are drab colored. Check it out. Carp are aquatic pigs, aquatic rototillers, roiling the sediments for food and muddying the water with suspended silt-clay. If that is beneficial for your pond management goals then there is nothing wrong with koi.
Last edited by Bill Cody; 06/17/11 09:23 AM.
