As posted on iNaturalist , “This Smooth Toadfish, Tetractenos glaber, has an odd growth or hypertrophic tissue response to something like a traumatic or parasitic injury on its head: –
It was very intimate with the numerous Rockpool Shrimp that always offer cleaning services in these rock channels and was loitering longer than the others of same size at cleaning station sites. I didn’t see any direct host client contact but have no doubt that it was happening before I approached closer.
I’ve no idea what caused the head lesion. The other adults-there were another 4-5 of this size in a loose aggregation (all appeared normal). This one swam normally but was clearly more agitated (which I’ve attributed to desperately seeking cleaning as noted above, although I don’t know how helpful any cleaner hosts would be in removing or reducing the size of this anomaly, since I don’t know the cause.
The nearest I can guess is that it reminds me of other Smooth Toadfish I’ve seen in the past, with light pink or red ‘rectal prolapse’-like extrusions from the anus, or perhaps very close to the anal orifice but not necessarily of enteric origin?
I’d always assumed that those apparent ‘rectal prolapses’ were the result of something akin to sudden excessive deflation of the self-inflated victim e.g. from being accidentally hooked and returned to the water by a recreational fisher, but this encounter throws much doubt on that theory.
If I had to guess, I’d say that the common theme was parasitic damage, perhaps ectoparasites but gastrointestinal tract ectoparasites not excluded (Palate/oropharyngeal and anorectal).
I wonder if the lesion originates from within the right nostril? Or from the fleshy, soft polypoid sensory papillae (R, vs normal on L) that are normal anatomical features of this species and are believed to have a role when the fish buries in the substrate.)
Here are some cropped images: –
