I've posted a bunch of videos of late, and realized that I don't have that many recent pictures.
A lot has changed in the last 6 months. The fish are all full size adults now, and all three species are breeding. They have their favorite shells that they hang out in, and don't stray far from them, especially the male blennies. When these fish are guarding eggs, most of the time, only their heads peek out of their oyster shells. They venture out and check out their perimeter of about a radius of 4", now and then, and further only at feeding time. They will eat, then bolt back to their shell. The female blenny is the lone exception, as she roams the tank and breeds with all of the males.
Much of the tank range of these fish are determined by these established territories, and these territories seem to be based on a pecking order, with the blennies claiming the best spots and defending them rigorously, especially against each other. However, since they don't stray far from their shell, confrontations are few.
The three species, for the most part, tolerate each other except when a fish moves too close to their favorite shell, and is chased off. The pecking order appears to be that the blennies are the most dominant, but pretty equal against each other, followed by the skilletfish but not far behind. Male skilletfish tend to defend their shells rigorously as well. The gobies are probably the least aggressive, but very brave, as they will put up a good defensive front against the other species and try to chase them away. They tend to back down and flee if challenged in return, though.
The females of each species are the most mobile and hold more vague territories, not necessarily restricted to a single shell. Here are some recent pics:
Female striped blenny (Chasmodes bosquianus)
Male striped blenny:
Male striped blenny, guarding eggs:
Skilletfish (Gobiesox strumosus):
Female naked goby (Gobiosoma bosc), the males look the same but are a bit larger: