Koi

Bernice Brewster

There are two elements that make up a Koi’s immune system. The first is non-specific immunity, which mops up any foreign body it encounters. The second part is the specific immune system. Here the cells of the immune system ‘recognise’ pathogens and cause a chain reaction of white blood cells to flood the infected area. The immune system is costly in terms of available energy and so the specific immune system is largely suppressed in the winter. The non-specific immune system runs continuously; no animal could afford to be completely vulnerable to any bugs looking for an opportunity to infect it. Spawning also affects immunity. Reproduction is the most important function over and above everything else and, as a consequence, the hormones that govern reproduction also suppress the immune system. Apart from natural causes, the other significant immunosuppressant is stress.