Myxobolus sp. can cause in vivo myoliquefaction in the host Paralichthys orbignyanus (Osteichthyes, Paralichthydae).

We found intense myoliquefaction in vivo among specimens of wild and farmed South American flatfish Paralichthys orbignyanus Valenciennes, 1839. The soft flesh condition was attrib- uted to Myxobolus sp. since the fish were not infected by myxosporeans which are usually associated with this condition (Kudoa spp.), and other causes (bacteria, fungi) were not found. The histopathol- ogy of the infection is described.