Members of the genus Kudoa primarily infect muscle tissue of marine fishes, where they form nodules or pseudocysts containing a great number of individual spores. In lighter infections these pseudocysts are isolated from the fish's immune system within the muscle fibre. More intense infections can result in severe inflammation surrounding infected muscle fibres. Although apparently asymptomatic in all but heavy infections, they are associated with post-mortem degeneration of the tissue. This softening of flesh is most likely a result the release of proteolytic enzymes by the parasite.