Symptoms

Symptoms Include :

Various sizes of white spots. Looks like someone threw a hand full of salt at the fish. However, sometimes the “spots” are so small they often go unnoticed.
“Flashing” rubbing against objects in your pond or aquarium.
Fish can become very lethargic, sitting on the bottom.
Heavy breathing caused by gill damage.

Note: New koi and plants can bring ich into your pond and aquarium. However, it has been found that some survivors of an ich outbreak can become carriers. On these “carriers” ich lives in a latent stage located at the base of fins or the gills.

Any stress or poor conditions can cause an outbreak of ich and re-infect either its host “the carrier” or other fish. This certainly seems to be the case with koi, when small numbers of ich (trophonts) are often found alongside severe fluke, Trichodina or Costia outbreaks, even in ponds which have not had any new fish or plants added.