This photo of some Magpie perch Pseudogoniistius nigripes is another example of this species tending to hog many of the most prominent Western Cleaner Clingfish Cochleoceps bicolor sponge stations under the Rapid Bay jetty: –
Rather than spending a short time at such a station, one gets the impression that they rest there for long periods, certainly many minutes, and possibly longer. Perhaps the species has evolved a special symbiotic relationship with Western Cleaner Clingfish? But many alternative explanations exist, and are speculation given the minimal science knowledge currently extant on this topic.
Options that spring to mind include:
The hosts have eaten their full, and while they are resting and digesting, the magpie perch gets the benefit of a safe place to spot potential predators.
Plus, being a fish that can oxygenate adequately when immobile, they will effectively be first in a queue, when the hosts resume cleaning as their appetite returns.
Alternatively perhaps, Magpie Perch are especially favoured by Western Cleaner Clingfish hosts? As bottom feeders, omnivorous but predominantly carnivorous, they rely heavily on winnowing to sift food from the mouthfuls of sand, etc.. that they routinely ingest. So their gills must be particularly susceptible to rapid accumulation of heavy parasite loads.
On another matter, I think tyat these two Spinytail Leatherjacket Acanthaluteres brownii are males in territorial dispute: –
Here is a cropped version of the photo for closer inspection: –
