How a Fish's Immune System Works


Unfortunately, many bacteria have ways to beat these defenses, either by producing a dissolving agent that destroys the fibrin and opens the way to infection or by releasing toxins that attack and kill white blood cells.


The kidney and spleen make antibodies specifically built to fight each particular antigen (invading disease). This process can take up to two weeks. The antibodies attach themselves to their antigen and fight it in one of three ways:


  1. Detoxify it – so that white blood cells can ingest and destroy it
  2. Attract a “compliment” – another blood component that helps destroy the antigen
  3. Deactivate reproduction – to stop the antigen proliferating


As in all immune systems, a familiar antigen is dealt with quicker than a new one. The system reacts quicker, antibodies already exist and they multiply extremely quickly upon contact with their antigen. This is the same principle used in vaccination, where a detoxified antigen is introduced to allow a fish time to build appropriate antibodies without danger. If the full-blown disease is encountered later, the immune system can gear-up much faster and survival chances are increased.


It is important to note that environmental pollution also hampers the immune system and reduces a fish’s response to pathogens.