Koi Herpesvirus (KHV) is a highly contagious virus that primarily affects koi fish and other carp species. It can cause severe disease, leading to high mortality rates, especially in young fish. The virus is typically spread through water and can survive in the environment for extended periods, making it challenging to control. Infected fish may show symptoms such as erratic swimming, gill lesions, and lethargy. There is currently no effective treatment for KHV, so prevention through biosecurity measures and good management practices is essential to protect koi populations from outbreaks.