I have lost two fish who seem to have dirt or old food coming out of thier gills? What caused this? -Dave

That dirt or old food is probably a fungus. A fungus is a secondary or tertiary infection. It basically means that something damaged your Koi and its immune system was weakened, so the fungus was allowed to take over. You need to find out what caused this and then take the appropriate action. Share: Del.icio.us Digg Reddit