12/15/2025
The days are flying by even faster since we changed over from Daylight Savings! And fall is certainly making itself known in my yard by the falling leaves from my Japanese Maple, esthetically but not practically planted right behind my pond's waterfall! This year we have placed black netting over the pond that catches roughly 75% of the leaves making maintenance of the skimmer more doable. A long handled net then makes easy scooping of the leaves laying on the net.
This time of year, with the weather getting cooler, we do need to pay attention to the temperature of our pond's water. 50 degrees is the suggested temperature to stop feeding our Koi as they cannot digest food properly at that low a temperature. Koi are cold blooded, and their internal temperature and metabolism match the water. Koi enter a natural, semi-dormant state called "torpor", slowing their metabolism drastically to conserve energy. They will typically move to the deepest, warmest part of the pond, stop eating, and remain mostly motionless. Koi survive winter by using fat built up in the summer and are equipped to fast. So, even if they appear to beg for food, it is out of habit and not hunger. Feeding them can lead to rotting food and serious infections. If you haven't yet, it's a good idea to have a pond temperature gauge to get an accurate reading of your pond water.
As far as koi diseases, some are year round threats. But some are more prevalent in cold water that you may want to watch for. Carp Pox (usually harmless and temporary), Koi Herpesvirus (dearly virus and needs immediate attention), Carp Edema Virus (causing lethargy, swollen gills with high mortality for juvenile koi), Bacterial infections (stress from cold water can trigger issues like Fin Rot or ulcers), and Parasites (can be more noticeable as fish gather, but treatment is tricky in cold water). Good water quality is a given and checking your fish for signs of disease throughout the year is always suggested.
Our club is not affiliated or endorses the following company, but they do have a good guide of Koi Diseases.
https://nextdaykoi.com
Happy Koi Keeping from the SCVK&WGC
