Chasing your Koi with a net scares them. Their natural instincts tell that that the end is near when in reality, you may just be moving them to their winter home. If you must net your Koi, doing to quickly and correctly will be minimally stressful. Never chase your Koi with a net. Instead, corral them into a corner and gently bring them to the surface. If you have a large pond, use a seine net the guide your Koi into a small area where they are easy to net. Once your Koi are at the surface, use a Koi tub, sock net or Koi transport bag to move them.
Bad Water Quality
Being exposed to bad water quality is detrimental to your Koi’s health. Ammonia is constantly excreted by Koi and most of it originates from their gills. Inadequate filtration or an uncycled biofilter can lead to elevated Ammonia levels in the water. Ammonia in the pond water affects the internal organs and nervous system of your Koi. Performing water changes and adding Ammonia binder to the water is a short term fix will reduce the amount of toxic ammonia in the Koi pond water. Adding more biological filtration and altering your Koi care protocols.
Keep a good environment and your Koi will take care of themselves (just add Koi food!). Preventing the sources of stress in this article will help your Koi thrive in your pond.