The social activity of fish is a strange and generally perplexing topic. There's a chance that the blenny will just watch its new mates from the background until it knows if it's going to be eaten, or try to eat someone else. Keep us posted.
My lawnmower always breathes like that, mouth open and fast enough to make me nervous (despite parameters always testing normal). I don't see what you are talking about with the right side eye and fin not Speed Test working.