Okay here is my last post on the subject. A qoute from Bob Fenner.
"Selection:
As with most territorial fish species, these blennies are best purchased small, and placed near last to provide your best chance at establishing a livable pecking order. How small is small? Two inches for Atrosalarias, two and a half to three maximum for Salarias spp.
Take care to not purchase a "too-thin" specimen that has been on hand and starved for too long, but on the other hand, don't be too anxious to acquire a just arrived individual either. Ones that are going to "die mysteriously" do so most often in the first few days of arrival.
Torn fins are not indicative of a doomed specimen, as these blenniids are rapid healers. Cloudy eyes, missing scales, sores on the body would disqualify a purchase however. Do watch/observe carefully for active, inquisitive behavior, hallmarks of a winning specimen.
Captive Habitat:
Expanding on the above environmental conditions, the size, maturity of a given system intended for these fishes is paramount in determining your successfully keeping them. Even starting with the smaller Atrosalarias fuscus or a very small specimen, a minimum of an undercrowded sixty gallons with this or more pounds of matured live rock is suggested. As you will find, these species claim an easy equivalent of bottom space as their own as this... With a hundred gallons per for a full size (five inch or so) Salarias fasciatus, being about right.
Tankmates:
These are by nature territorial fishes, that will drive out other animals, including of their own kind, from their algal patch area... how to put this.... with extreme prejudice. Algae eating tangs like Ctenochaetus, many Zebrasoma, small Rabbitfishes/Spinefoots... sessile invertebrates that make their living rasping the bottom, may have a tough go at living in the same small space as these blennies. If you would like to try mixing them, do place the blenny last.
Other blennies/oids and families of fishes are generally ignored, or just chased for the halibut by algae blennies, as long as their not filamentous algae eaters. "