Blennies don't "host", but they will pick out a spot to retreat to...and your leather may be what he prefers as cover that he would use to hide under/around in the wild.
I have had probably a dozen BTA's over the years, and they have all had SOME differences in behavior...probably due to being in the different setups I've had. BTA's do anchor to a rock. They will move about for some/no reason. They do move out/up into light when it's available. I have one that will stretch one way toward halides when it is cloudy out, but in the evening when the sun shines in as it is setting - it stretches out away from the halides and toward the sun.
Your clowns may never host in the BTA...but I have found almost ALL will but it may take weeks, even months, for them to recognize the BTA as a host. What kind of clowns do you have?
