The Frog Blog – Fish Friday

Many people who own ponds and water gardens on their properties enjoy them for their aesthetically pleasing properties. They become an oasis of beauty and relaxation for those moments when you need to get away. Therefore, it isn’t too surprising that many wish to enhance these places with beautiful and eye catching colors and sounds that add to their relaxing properties. Koi are a common way for pond and water garden owners to add color and life to their aquatic ecosystems. However, many are unaware of the impact these organisms can have on the water quality and management of their systems if they are not added with consideration and planning.

Koi are actually very closely related to the common carp (Cyprinus carpio) that is found throughout the state of Ohio. Anyone who has seen these two fish knows that their body types are very similar and are well designed for a benthic (bottom-dwelling) life in water. Since they live near the bottom, they have a tendency to push sediment around causing it to flare up into the water column. This can cause a murky look to your pond or water garden that many find displeasing. Their benthic lifestyle also can rip up macrophytes (aquatic plants and macroalgae) that may be rooted into sediments and cause them to float to the surface. For some species like the invasive Eurasian watermilfoil (Myriophyllum spicatium), this means they can spread to different parts of the pond since they can reproduce from fragments. Both increased water turbidity and macrophyte fragmentation can make management of the pond more difficult and costly.

When deciding whether to add Koi to your pond or not remember to do some research first. Make sure to purchase the correct quantity and size fish relative to the size waterbody you own. Also be sure to purchase them from a reputable source as Koi can commonly carry diseases. By doing this research and correctly stocking your fish you will be able to enjoy the beautiful colors Koi can provide while also limiting the potential for reduced water quality.

By: Edward Kwietniewski

Aquatic Biologist

AQUA DOC Lake and Pond Managment

Edward Kwietniewski graduated from The State University of New York College of Environmental Science and Forestry (SUNY ESF) with a Bachelor’s degree in Aquatics and Fisheries Science. He also has a Master’s degree in Lake Management from the State University of New York College at Oneonta (SUNY Oneonta). He has a love for all things aquatic and is an avid fisherman.