thanks for your reply ! I'm not sure it's hole-in-the-head, though, perhaps the larger images in the gallery show it better but it seems to me the ooze starts off from the [b]inside[b] and eventually breaks through the skin (as if lymphs or some other fish anatomy-related points get infected). Don't let the size of the sniffing/breathing hole (? if that's the name in english) above the mouth fool you, the image is a really-really closeup (the whole fish is 6-7cm long)