That Fish Blog – Aquarium Advice and Information

Patty here. Koi  are basically colored Carp.  They are descendants of Asian and Central European Carp originally domesticated and used as food in China and Southeast Asia.  Their hardy nature and adaptability made them easy to propagate and transport to new locations.  Beginning over a thousand years ago, Asian breeders were selectively breeding these fish to develop natural color mutations into the brilliant and brightly colored fish that exist today. By the early 19th century through the early 20th century, desirable color patterns were established by the Japanese, and Koi started gaining world -wide popularity. 

As Pond season rolls around this year, many might be considering the addition of Koi to a water feature. Here are a few tidbits to think about before you purchase koi.

• Koi should only be housed in ponds at least 1000 gallons or more. The bigger the better. The depth of the pond should be at least 3 feet to help the fish to avoid overexposure to sun and heat and to allow them to survive harsh winter temps. If your pond does not fit these criteria, goldfish and comets will be a better fit for you.
• The bright colors shown by koi make them beacons for predators. Herons, raccoons, bears, and even cats and dogs amongst others may find koi a fancy meal if they can reach the fish. Proper depths and shade trees can help the fish to stay safe.
• Koi have big appetites. They are omnivores, and will enjoy a varied diet of staple pellets along with frequent treats of fruits and veggies like watermelon, peas, lettuce, and corn. Koi will also eat plants at the surface of the water and will happily dig at the roots of potted plants on the pond too. You may need to cage the plants to preserve them, or at least top the soil with river rocks.
• By encouraging these fish to the surface for feeding, they can become quite tame, often hand feeding. This behavior allows for visual health inspections that may need to be treated.
• Koi should not be fed if the temperature of the pond sees a constant of 50 degrees or lower as they cannot properly digest proteins.
• Along with their big appetites comes a lot of waste. Be sure to provide ample filtration and aeration particularly if you have a number of these fish in a minimally sized pond.
• If provided with a proper environment, koi can live for decades, and have even been reported as living more than 200 years!
• Wild carp can grow to almost 6 feet in length, and ornamental koi are known to reach lengths of about 3 feet in length. Carefully consider this in relation to the pond you plan on housing the fish in as they grow QUICKLY! Juvenile fish can double in size in a year, and though the growth rate can slow after 2 or 3 years, the fish continue to grow for 10 to 15 years. They’ll need plenty of space to grow and live comfortably.
• Koi spawn in the spring. Females grow bloated with eggs and males compete for the opportunity to fertilize the eggs when she releases them. You may see one fish being chased aggressively around the pond by several others. The female is the target of the attention. Supply breeding mats, floating plants, or plants at the bottom of the pond as a place where she can release her eggs. You may be lucky enough to see new additions to your population not long after, though survivability is usually not high unless the fry are collected and nurtured.

Koi can be the pride of a backyard pond, but they do require a bit more attention and a lot more space than goldfish and comets.  When you’re ready to add fish, give us a call or shoot us an e-mail with any concerns or questions so we can help you to have a successful pond experience.  Be sure to save the date for or annual Pond Festival, too, May 16-17 2009!

Image referenced from Wikipedia and originally posted by Stan Shebs